text:
600. You do not really have a preference. You
will offer either/or.
(Dr Prudo-Chlebosz) Yes.
601. What do you think about what you have just
heard, Mr Spiller?
(Mr Spiller) It is inappropriate if they are individual
contracts for both to be on offer because this will create huge
problems. If we were looking at this in a year's time, we would
have a different attitude to it, and so would the private sector.
I come back to agenda for change. Huge changes are taking place
both in pay levels and in the way in which pay is determined.
Some of the advantages which are perceived at the moment in the
private sector will disappear because we believe the NHS arrangements
which will come through agenda for change will be so much better
than they are at the moment. We have been working for this very
result for many years and we are pleased to see it on its way.
One other thing I really need to say is that terms and conditions
of employment are not necessarily the major issue that even we
are concerned with. One way or another we know that the employer
will have to pay sufficient to recruit and retain. That is a given.
What we are more concerned with is the long-term viability of
this process, particularly if the employer changes, as could happen
for example with Ealing; having gone from the NHS to TDL, it could
now go to Quest and that is a big concern. We are having this
continual change of employer and although TUPE is there, it can
create enormous difficulties when you are taking people in from
different areas, some coming from the NHS, some coming from another
private provider. We had this experience in the private sector
with contracting where it creates huge anomalies, where people
can stay on their previous terms and conditions of appointment
and be working alongside somebody on different terms of employment.
You can have three separate terms and conditions of employment.
A computer company we deal with has 42 different sets of terms
and conditions of employment as a result of TUPE which it has
to operate within the same company; an almost impossible task.
Our preference is that there should be retention within the NHS.
We believe there is an important case to be made for introducing
additional management into the NHS, there is a shortage of good
management at the moment. The private sector may well be able
to provide this and they may well be able to provide other elements
and new ideas which are perhaps not in the NHS at the moment.
We believe there are ways of doing this without changing the status
or position of staff.
602. Would you therefore see a viable model
for the pathology service being the facilities, laboratories,
capital equipment provided through the PFI route, staff employed
by the NHS? Would that enable you to get the money into the modernisation
of the bricks and mortar? Would that be your preferred model?
(Mr Spiller) We take a pragmatic view on whether the
private sector should be involved in those circumstances. If it
delivers a better service to the patient at a better price, then
we have no objection to that happening. The proposal you have
put forward, the model you have put forward, is one we could certainly
live with and where we could see some advantages.
603. Does Ms Wannell's evidence not suggest
that when the staff are also employed by the private sector, the
quality is improved as well? Thinking about the service to patients
and not just about the conditions of the staff, is there not some
evidence that that has introduced quality gains?
(Mr Spiller) No. No, the evidence on improved quality
gains comes largely from the investment which is going in. Pathology
has been starved of investment over the years and what we see
now is the private sector coming along and putting investment
in and that is why there is a big improvement in quality. It is
not down necessarily to the way in which people work or their
capabilities. One has to say as far as the private sector is concerned
that where it previously existed, it has existed either because
the private health sector was using it or the pharmaceutical companies
and they had to have high standards.
604. Has the introduction of a contract focused
attention on performance in a way that there was no direct lever
on performance under the old system? Would you accept that?
(Mr Spiller) No, I do not think so. One of the areas
of difficulty we find in contracts is that the transaction costs
can be quite significant on occasions. One of the costs we are
finding with private sector, or fears of our members have been
expressed in this way, is double testing. Where a test comes out
as not truly abnormal, but on the other hand not quite right as
well, in a NHS laboratory this will always be investigated further
at the initiative of the scientist who is dealing with it. The
worry we have is that where there is a contractual arrangement
which is trying to drive down the number of tests done, albeit
that is what is required clinically, these opportunities are not
there. They are much more cost conscious. That may be a good thing
and it may be that one should get authority for those additional
tasks but that happens at the moment and one can give a GP an
answer which he was not expecting because you have done something
extra which he did not ask for.
605. West Middlesex seem to suggest they have
solved this by having it clinician-led. Would you not accept that
that always works?
(Mr Spiller) It is always clinician-led in that sense.
What we are trying to do is break away from it having to be clinician-led.
606. What they are suggesting is that no-one
would stop doing something because of a cost pressure. If it deserved
further investigation they would do that.
(Mr Spiller) No, no. I do not think that is necessarily
607. I should like to come back to an expression
you used a few moments ago about a shortage of management in the
Health Service. Did you mean there are just too few managers or
high vacancy levels or there is not enough management skill within
the NHS? What did you actually mean by that?
(Mr Spiller) That was a mistake of my own making because
we represent managers as well in many areas. There are several
features. The first is that the management structure in the NHS
leaves a lot to be desired; we and indeed the DoH have found the
independence of trusts has been a major problem. Secondly, the
management style has been governed for the best part of 20 years
by managers trying very hard to drive costs down and sometimes
reduce resources and it takes time to change that management style
around. Thirdly, there is simply a shortage in numbers of management
and fourthly, there is something left to be desired among a lot
of NHS managers as to levels of competence. In all respects I
can see that there will be areas of the private sector which could
help with that, certainly in terms of it lifting the number of
good managers within the NHS. There is no question that we are
short of good managers in the NHS and that is not in itself denigrating
existing managers, it is simply that we are asking too much at
the moment of managers to deal with the move to PCTs, where there
is hardly any HR component.
608. I am still not clear whether you are emphasising
better managers or more managers.
(Mr Spiller) More managers.
609. More and better managers.
(Mr Spiller) More managers; one would hope obviously
that they would be better.
610. Earlier you were suggesting that in terms
of improving the career prospects of your members, particularly
technical staff in the service, there was an indication that things
were getting a little bit blurred between the clinical pathologists
and staff in that your members were beginning to take more decisions
than perhaps they used to. I think that is an excellent idea and
it reflects things which are happening elsewhere in the National
Health Service: radiology and radiographers for instance are becoming
a bit blurred and some of the things doctors used to do which
nurses are now being entitled to do by legislation. I just want
to know whether you think that is going to happen more. Then I
am going to ask Professor Lilleyman what he thinks about that.
It is a very interesting area. Do you think it is likely to carry
on expanding, particularly in the light of what else we have been
hearing this morning about separating off technicians in the service
from the actual hospitals and a central organisation which might
be a long way away from where the clinical decisions are made?
(Mr Spiller) It is a trend which is developing for
very positive reasons, partly driven by the shortage of consultants
and looking at ways of trying to enable the decisions to be made
which consultants would otherwise be doing. An example of this
is that one of the sections of our union, the medical practitioners'
union, has recently proposed that the new surgical diagnostic
units which are being proposed should be run by nurses and operated
by nurses rather than doctors, that many of the features of those
could be done by well-trained nurses rather than necessarily using
doctors to do that. Some very fundamental changes are being proposed.
Intermediate level of professions is something which is seen as
being much more desirable now, much more possible, It happens
in many other places in the world. We have very clear professional
lines of accountability in the Health Service in Britain. That
is going to become blurred as there is going to be much more work
across professions and across departments.
611. You certainly see this as a positive move
for the people you represent.
(Mr Spiller) Most definitely. Even though some of
our members' work will be given to people who might be seen as
being lower skilled than they are, we see this as a positive move
both to reduce the shortages which exist, but also to be more
positive, to give people a higher level of skills and better commitment
to the work they are doing.
612. Professor Lilleyman, far be it for me to
suggest that your College is equivalent to a trade union, but
what do your members feel about this kind of thing?
(Professor Lilleyman) May I first of all point out
that 20 per cent of our members are not doctors and we are unique
as a medical Royal College in that regard. It is something we
are actually rather proud of and that constituency is increasing.
That in itself is a testament to the fact that we have no difficulty
whatsoever embracing the skills of our scientific colleagues.
I should point out something which has not actually arisen this
morning so far and that is that there are three professional tribes
in NHS pathology, not just two as we have been talking about.
We have the medical practitioners, we have clinical scientists,
who are separately regulated under the Council for the Professions
Supplementary to Medicine and we have the MLSOs. The fuzziness,
the blurring of the boundaries is not just going to occur between
the scientists and doctors, it is also going to occur between
two different types of scientists. Witness to this fact of course
is that those two tribes are already merged into one in the independent
sector. They do not exist as two separate tribes outside the NHS.
I and most of the members and fellows of the College would have
no difficulty at all embracing flexible working in all its aspects
in the delivery of pathology services. We see this as not only
essential due to workforce problems but highly desirable from
a professional point of view.
613. Are you encouraging it?
(Professor Lilleyman) Yes.
614. Karen Ward, how do you see this when what
you want really in the setup you are proposing is to have a much
more factory scale thing where you get through more and more tests
in as short as possible time, in some cases away from the clinical
setting? How do you see this fitting in with your plans?
(Ms Ward) Everyone has this fear of the factory laboratory
and most people seem to focus on that as the big issue for them.
615. Reassure us.
(Ms Ward) Our approach is that the configuration of
a laboratory, where it is, how big it is, what tests are done
there, is really the last decision which is made. We always start
from the premise that you design a service based on the needs
of the users of that service. If the clinicians of an acute trust
have a particular profile, they have oncology clinics, they may
have rheumatology clinics, then the service is designed to support
that clinical activity. Once you have done that with all of the
users of the service, designing the laboratory to support that
activity is a relatively easy step. It is not a decision we as
a company would make on our own. We feel one of the problems with
the current procurement process, for example, is that it keeps
people apart for too long a time. You really need to involve the
professional groups at a much earlier stage. They are the ones
who are going to have a big impact on how services can best be
delivered. What we see as a partnership is bringing together the
strengths of the two parties. It is not a question of a company
like ourselves coming in and saying this is how it is going to
be folks, like it or lump it. It is a question of working in partnership
as we do with the consultants at the West Middlesex and the staff
of the West Middlesex and many of our staff are key people in
determining changes to service provision. As far as we are concerned,
they all have a contribution to make. There is no one particular
organisation which holds sway over any other, it is a true partnership.
Gail Wannell was talking earlier about looking at how services
are best used. It is not in our interest for the use of the service
to go through the roof, because if the trust cannot afford to
pay for that, then that is not in their interest or in our interest.
What we are aiming for is appropriate use of the service, use
of the service based on best practice, based on testing protocols
so that there are clear paths through to audit, so you can see
that what you are doing in a laboratory is providing benefit to
the doctors and to the patients who are using it. Roger's comments
earlier on about the staff being concerned about not being able
to do additional work on samples is certainly something our staff
would find a complete anathema.
616. What would they do if they came across
such a situation?
(Ms Ward) Exactly what they did before the partnership
617. Which is?
(Ms Ward) If a specimen needs further tests then that
would be done. It is based on clinical need and they are as responsible
people as you would find anywhere. They are very highly trained,
very highly skilled and in their view, they are looking after
the patient just as much as anyone else is. We would expect them
to do that. Our response would be that if someone did not perform
an additional test because they were concerned about being allowed
to do it under the contract, that would be the wrong approach
as far as we were concerned.
618. Do you lose money as a company when they
do that further testing?
(Ms Ward) I am not sure I can answer that question
because the service is designed to produce outcomes. What we are
looking at here is delivering a service, we are not delivering
a certain number of washers. What we are trying to do is provide
effective management of a particular patient to the trust. If
we were to say, for example, that we do not do that test and we
have to wait for it to be requested by the doctor, that patient
would stay in hospital longer. What we are saying is that no,
we are there to provide a service, we are there to provide effective
services to the trust. Anything that helps the trust treat that
patient better and the doctors treat that patient better is a
good thing for both of us.
619. I want to give Dr Prudo a chance to say
what he thinks about this.
(Dr Prudo-Chlebosz) In addition to what has been said,
modern technology is driving much of this. When we went to Ealing,
most of the pathology reports were signed off by a consultant
pathologist. We introduced rules-based reporting which is that
the consultant sets up a set of rules and these are incorporated
in a software programme and you only sign off exceptions.


text:
|Publication number
|Publication type
|Application number
|Publication date
|2 May 1995
|Filing date
|22 Sep 1994
|Priority date
|22 Sep 1994
|Fee status
|Publication number
|Douglas W. Dewey
|Original Assignee
|International Business Machines Corporation
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (16), Non-Patent Citations (6), Referenced by (68), Classifications (11), Legal Events (5)
|External Links: USPTO, USPTO Assignment, Espacenet
1. Field of the Invention
The present invention pertains to optical storage media for computers, and in particular is concerned with error recovery and data reconstruction schemes for optical disks which is particularly useful in automated storage libraries.
2. Description of the Related Art
Several techniques for error recovery and data reconstruction of data stored on disks are presently known. Reliable techniques include disk mirroring and the use of redundant arrays of inexpensive disks (RAID). Each technique has its own merits and disadvantages, but no known technique is particularly well suited to optical disks because of their unique data format. Additionally, optical disks are often dispersed among several storage areas that are accessed by one or more robotic mechanisms controlled by a central computer. These storage areas are referred to as automatic media storage libraries, or automated libraries. A concept, analogous to RAID, called redundant arrays of inexpensive libraries (RAIL) allows multiple storage libraries to be controlled by one central computer; however, known RAID techniques for error recovery and data construction are inefficient when applied to optical media stored in redundant libraries due to the large number of disks involved.
Referring to FIG. 1, a prior art example of a disk mirroring system is shown. File 13 is written by an application program 12, and then sent by an operating system 10 to a control program 20. The control program simultaneously sends identical copies of the file to the drives 22 and 24. The copy of the file stored on drive 22 is "mirrored" by the copy stored on drive 24. In this example, the two drives 22 and 24 represent the minimum configuration for mirroring. Mirroring can be used to improve performance in normal operation. For example, when a file is to be read from mirrored disks 22 and 24, the control program 20 reads alternate file clusters simultaneously from each of the drives and passes them by way of the operating system to an application program. For example, clusters 14, 16 and 18 are read from the copy of file 13 on disk 22 while clusters 15 and 17 are read from the copy of file 13 on disk 24. Obviously if three or more drives are used for mirroring then the performance of a file is increased; however, the trade-off is that the cost also increases with the addition of each disk. Mirroring is especially useful when a read failure occurs, such as one caused by a media surface defect or by a read head "crash". In either case, the whole intact file 13 can be recovered from the other disk. Further, if the failure is due to a media defect, then control program 20 may repair the disk experiencing the error by rewriting the missing data from file 13 stored on the undamaged disk. The primary disadvantage of mirroring is cost. A dedicated disk drive must be available to replicate each disk drive of interest.
Another technique used for error recovery and data reconstruction, less expensive than mirroring, is known as Redundant Array of Inexpensive Disks (RAID). A research group at the University of California, Berkeley, in a paper entitled "A Case for Redundant Arrays of Inexpensive Disks (RAID)", Patterson et al., Proc. ACM SIGMOD, June 1988, describes this technique. A RAID 1 architecture is essentially disk mirroring described above. A RAID 2 architecture uses "bit striping" in which each bit of each word of data plus error detection and correction (EDC) bits for each word are stored on separate disk drives. For example, a 32-bit data word might have 7 EDC bits added using the known "Hamming code" technique. The 39-bit word must then be written one bit per disk drive onto 39 disk drives. If one of the 39 disk drives fail, a control program may use the remaining 38 bits of each stored 39-bit word to reconstruct each 32-bit data word. A significant drawback of RAID 2 architecture is that a large number of disk drives are required, and that seven of the drives must be dedicated to bit striping EDC data.
U.S. Pat. No. 4,092,732 to Ouchi describes a RAID 3 architecture. RAID 3 architecture is the predecessor to more recent generations of RAID architecture, including the widely implemented RAID 5 architecture. RAID 3 architecture is based on internal error detection and correction, so that it is not necessary to provide extra error detection and data correction, as in RAID 2 architecture.
Referring to FIG. 2, an example of a direct descendant of a RAID 3 type architecture is shown. A file 33 is written by an application program 32 and eventually passed to control program 40 for storage on a disk. The control program simultaneously sends one-half of the file clusters (34, 35, and 36) to drive 42 and the other half (37, 38, 39) to drive 43. Drive 44, which does not receive file data, is reserved as the "parity" drive. The control program 40 performs an Exclusive OR (XOR) operation on the data being written to drives 42 and 43. The result is parity data, written to drive 44. An XOR operation results in a "0" bit whenever two identical bits are compared, and a "1" bit whenever two dissimilar bits are compared. For example, cluster 34 of file 33 contains the byte 50 comprised of the bits "1100", and cluster 37 contains the byte 52 comprised of bits "1010". An XOR operation yields the following parity bits 53 comprised of "0110". This parity information written to the parity drive can be used to reconstruct the data in the event of a read failure by performing a reverse XOR operation of the undamaged bits with the parity bits. Three is the minimum number of drives for a RAID 3 architecture, but there is no maximum limit. However, there is a marked decrease in performance caused by an increase in the number of drives to which parity bits must be written. If there are more than three drives in an array, the first two are XORed and that result is XORed with the next drive, and so on until all the drives containing data have been XORed and the final result written to a parity disk. An obvious advantage of RAID 3 architecture is that for "N" number of disk drives, only one additional parity drive is required. Thus "N+1" disk drives define a "redundancy group". On the other hand the disadvantage of RAID 3 architecture is the performance overhead required to read each bit of data, perform multiple XOR operations, and write the data to a parity disk.
U.S. Pat. No. 4,761,785 to Clark et al. describes a RAID 5 architecture in detail. A RAID 5 architecture revises the RAID 3 scheme by distributing the data and parity information across all available disk drives. Typically, a redundancy group of "N+1" drives are divided into a plurality of equally sized address areas known as "blocks". Each drive generally contains the same number of blocks. Blocks from each storage unit in a redundancy group having the same unit address ranges are referred to as "stripes". Each stripe has N blocks of data, plus one parity block on one drive containing parity for the remainder of the stripe. This technique is commonly referred to as "parity striping". Further stripes each have a parity block, the parity blocks being distributed on different storage units. In this way, no single unit is burdened with all of the parity update activity. A limitation of RAID 5 architecture is that a change in a data block requires a considerable performance overhead, as both the parity block and data block must be read and XORed, and the result XORed with new data. Then both the result (the new parity block) and the new data must be written to disk drives. Any requests to read or write new data during the period when parity is being updated must wait until updating is completed. This performance overhead is commonly referred to as the RAID write penalty.
A method for parity protecting distributed files in a parallel network is disclosed in U.S. Pat. No. 5,130,992 to Frey et al. This invention is useful for spreading parity among a large number of devices; however, the '992 invention involves updating a parity block whenever data is written in a file that is parity protected. The disadvantage of immediate updating is the overall impact to system performance as the data is read, a parity operation performed, and the new data is written. Another method which builds on RAID 5 techniques to reconstruct redundancy information during normal or "online" operation is described in U.S. Pat. No. 5,235,601 to Stallmo et al. Applying such an "online" technique to a large number of disks (e.g. in a storage library) would also have the inherent disadvantage of slowing throughput, because a parity update would be required for numerous disks after every write operation.
A method of reconstructing data without the necessity of continuously updating a parity redundancy is disclosed in U.S. Pat. No. 5,124,987 to Milligan et al. The '987 invention involves writing new or modified data to non-permanent electronic memory, in the form of "logical tracks". A background process compares the new data on a "logical track" to any old data stored in a previous write and removes the old data. The data is periodically written to physical tracks which serve as redundancy drives. By using logical memory to perform periodic reads, the '987 method improves performance over conventional raid techniques that use only disk memory for storing redundancy information. However, the tradeoff is the inherent risk of relying on volatile non-permanent memory for data construction. There is a risk that the contents of volatile electronic memory will be lost once power is interrupted.
RAID techniques have typically been used with magnetic drives, such as the type of Direct Access Storage Disks (DASD) units, which are often used as conventional hard drives in personal computers. RAID architecture is not typically employed in magneto-optical units, because these units have pre-erased sectors. The pre-erased sectors are usually created before shipping and a formatting operation is employed to ensure that the pre-erase has been completed. The pre-erase creates all 0's throughout the disk. This is done because of an inherent inability of a laser beam used in magnetic-optic technology to write 0's and 1's simultaneously. Typically, a full revolution of the disk is required for a "write pass" (writing 1's) and another revolution is required for an "erase pass" (writing 0's). To avoid the erase pass, the disk is pre-erased before any writing of data is allowed. As data accumulates, the area devoted to pre-erased sectors decreases but the presence of them presents a problem for calculating parity. The pre-erased sectors contain logical blocks of data that would be treated as "0"'s in a conventional parity striping algorithm. The resulting overhead involved with creating parity data for a block of "0"'s is completely unnecessary, since the data will not change as long as the sector remains erased. Alternatively, the pre-erased sectors might send a conventional RAID parity striping program into error recovery mode, reducing performance and inducing errors itself. Entering error recovery mode reduces performance and therefore should be avoided if possible.
One objective of the present invention is to apply a reliable "parity striping" feature for optical disks without increasing performance overhead.
Another objective of the present invention is to apply parity striping to optical disks without inducing errors caused by reading pre-erased sectors.
Another objective of the present invention is to allow "parity striping" to occur for optical disks stored in a Redundant Array Inexpensive Library (RAIL) scheme without significant performance overhead.
In accordance with these objectives, the invention provides an apparatus and method for performing parity striping of optical disks, which is done either partially or fully off-line or upon exporting a parity group from the storage array. In one embodiment, the invention is implemented with any array of redundant optical disks. In another embodiment the invention is implemented with a redundant array of independent libraries. In either embodiment, striping may be performed only when the media is archived to an external shelf. Advantageously, the creation of a parity striping redundancy groups upon export does not impact the performance of the system. Further, the technique is reliable since data is written to permanent storage on optical disks, rather than relying on electronic memory to store redundancy data.
A striping method and apparatus which is "aware" of the media format for the data is capable of recognizing pre-erased sectors inherent to magneto-optical media. The utility utilizes the format to reduce the work of striping and reconstruction. Because the system is programmed to recognize the pre-erased sectors, no error recovery is induced. When the parity information is created, the location of data blocks having pre-erased sectors is recorded in memory. A map of these locations referred to as a free space map is stored in memory. The map is referred to when calculating parity so that it is not necessary to read the area allocated to pre-erased sectors. The map is used to avoid errors which would be induced if the pre-erased area was read prior to calculating parity, and to allow parity calculation to precede in an expedient fashion.
The foregoing, together with other objects, features and advantages of this invention, will become more apparent when referring to the following specification, claims and the accompanying drawings.
FIG. 1 shows a prior art data reconstruction technique using disk mirroring;
FIG. 2 shows another prior art data reconstruction technique using parity striping with a redundant array of inexpensive disks;
FIG. 3 shows a redundant array of inexpensive libraries storing optical disks that is useful with the present invention;
FIG. 4a is a simplified sketch of a data format for storing data on an example of a data storage medium useful in the present invention;
FIG. 4b is a more detailed sketch of the data format of the exemplary data storage medium shown in FIG. 4a;
FIG. 5 is a flow chart showing an overview of a method of building all parity at one time which is useful with the present invention;
FIG. 6 is a continuation of the flow chart of FIG. 5;
FIG. 7 is a more detailed overview of part of the flow chart of FIG. 5;
FIG. 8 is another more detailed overview of another part of the flow chart of FIG. 5; and
FIG. 9 is a flow chart showing an overview of a method of building parity on an intermittent basis which is useful with the present invention.
Referring to FIG. 3, a redundant array of optical storage libraries is shown. It should be noted that the invention may be employed to build parity data for any plurality of data storage mediums. However, the invention is particularly advantageous for management of parity data for a library type environment. The present invention is particularly useful with optical media stored in redundant libraries. However, the invention is also useful when employed in an environment of only one library, such as a library 92. For exemplary purposes an array of libraries containing one or more libraries is shown. The combination of libraries 92, 94, and 96 form a known RAIL architecture which is useful for implementing the present invention. Exemplary library 92 contains a plurality of drives 64-67 used for reading and writing data on one or more data storage mediums, such as mediums 81a-f. The mediums 81a-f are each stored in a respective storage bin 91a-f. The bins collectively form storage unit 86. The quantity of bins shown is merely for illustration and in actual practice may be more or less than the quantity shown. Regarding terminology the data stored on a data storage medium, such as medium 81a, is referred to as a "volume". For purposes of this disclosure the term volume is used interchangeably with data storage medium as a short way of referring to data stored on a particular medium. In a similar fashion, data volumes 83a-f are stored in bins 93a-f, respectively. The bins 93a-f collectively form storage unit 88 in library 94. Likewise in library 96, volumes 85a-f are stored in bins 95a-f, respectively, and the bins form storage unit 89.
A library control unit 62, which may be a personal computer, such as an IBM PS/2, is shown coupled to a host processing unit 60 through an input/output (I/O) channel 69a. The host may be, for example, an IBM 3090. A host computer, such as the IBM 3090, has within it code for processing job requests within a data storage library. The control unit 62 is used to process commands from the host 60, and to manage each respective library 92-96 through special control logic 58 which is part of the control unit. The control logic 58 may be hardware or software and is used for implementing the methods described in this disclosure. The control unit 62 through logic 58 controls an automatic robotic picker and a plurality of drives in of one of the libraries, such as library 92, through control bus 69b. In a preferred embodiment, the logic 58 is implemented as software in the known C programming language. One skilled in the art will recognize that the logic 58 could also be implemented in a microprocessor 59 as microcode (not shown). Electronic memory 61, which may be conventional random access memory (RAM), is part of the control unit 62. In a preferred embodiment the software embodying the logic 58 is loaded in the electronic memory 61 for execution. The electronic memory could be implemented as volatile or nonvolatile cache, however, a conventional RAM configuration is preferred because it is typically less expensive, and is adequate for implementing the method of the invention. The memory 61 is also used for storing information obtained during a read of data stored on an optical storage medium, such as medium 81A, which will be used to read and calculate parity data. A permanent storage unit 63, which may be a conventional hard drive, is coupled to the control unit 62 for storing host updates and other information related to updating data and parity. The logic 58 may be stored as a software program on storage unit 63 so that it is available for loading the logic into the electronic memory. The logic as a software program is executed by a control microprocessor 59. The microprocessor can be any conventional microprocessor such as an Intel 80486 available from the Intel Corporation.
Several automated storage libraries are known. IBM Corporation introduced the 3850 mass storage subsystem for retrieval of magnetic tape modules in the 1970s. More recently, several automated storage libraries for magnetic tape cartridges and optical disks have been introduced. Examples of optical disk libraries can be found in U.S. Pat. Nos. 4,974,156 and 4,945,428 assigned to the assignee of the present invention. Also systems for general automated libraries capable of handling either tapes or optical disks are described in U.S. Pat. Nos. 5,121,483 and 5,197,055, also assigned to the assignee of the present invention. The robotic picker mechanisms of these libraries include one or more grippers. Each gripper is capable of handling one data storage medium at a time. By grasping a data volume with a gripper, a picker can retrieve a volume from a storage bin and place it in a drive unit. A library useful for implementing the invention, such as library 92, may be any one of these known libraries.
Each library 92, 94, and 96 has a dedicated robotic picker 70, 71 and 79 respectively. In the event of a picker failure the data stored in respective storage units 86, 88 and 89 in each library would be inaccessible. However, the present invention enables accessing of the data by distributing parity information outside of the library. For example, in the event of a mechanical failure of picker 70 belonging to library 92, data for which a redundancy group has been created and stored outside the library could then be loaded into library 94 by picker 71. The data could then be read in a particular drive or drives in library 94, such as drives 68-74. A similar arrangement in library 96 allows reading of data on a storage medium, such as medium 85a, on drives 75-78. Physical and logical data formats of data storage mediums useful for implementing the present invention are described below.
Referring to FIGS. 4a and 3, an example of a file system format for an exemplary optical data medium, volume 81a, is shown. FIG. 4a shows a physical representation of the data format on the volume 81a. The volume 81a is shown for the sake of simplicity as representative of the preferred format for all of the volumes used to implement the present invention. In a preferred embodiment, the present invention is useful with a known fixed block architecture (FBA) format; however, the invention is also useful with other known formats such as count key data (CKD) format. A parity-- control-- block 106 is used to define control parameters related to creating parity, and is created by control logic 58 to enable the methods of the present invention. The remaining blocks shown comprising addressable space on represented volume 81a are known data structures common to optical data storage mediums, where the data blocks are arranged according to the preferred FBA format. The parity-- control-- block is used to manipulate the data blocks in heretofore unknown ways to create parity data. A physical block 102 representing written sectors is available for storing user data and system control data. A physical block 104 representing pre-erased sectors is used to represent those sectors erased during a formatting operation of optical disks, such as those used in magneto-optical technology. However, the invention is useful with any technology which has erased sectors and is therefore not limited to just optical disks. A convenient choice for the size of a sector in the preferred FBA format is 1024 bytes. Within the entire volume 81a there is a plurality of sectors which may be addressed by specifying a "range", where a range denotes a contiguous set of sectors, for example a range may be specified to equate to 64 contiguous sectors on volume 81a. A plurality range spanning the entire volume 81a comprises all sectors contained in physical blocks 102 and 104.
Referring to FIG. 4b, a detailed logical depiction of the data format of volume 81a is shown, which includes logical data shown in blocks 106-120. The physical written sectors block 102 is shown comprised of a plurality of logical blocks 108-118. A "reserved file" block 108 is used to store system control information which is not particularly relevant to the implementation of the present invention. A pair of "user data" blocks 110 and 118 are each used to store data written by a user application. There may be more than the single pair of user data blocks shown, but two are shown to indicate there will almost certainly be a plurality of such blocks. Each user data block 110 and 118 is pointed to by a directory file in block 116, so that the location of user data may be obtained by control logic 58 simply by reading the directory file. The directory file is further pointed to by the reserved file in block 108 to indicate to the control logic the location of the directory file on the volume 81a. A freespace file in block 114 points to a block 112, which has been written but is no longer allocated, for example, such is the case of a file that has been marked as being erased but has not been physically removed from the disk. The freespace file further points to pre-erased free space in block 120 created for an optical disk. The erased free space in block 120 is the logical component of physical pre-erased sectors shown in physical block 104.
Referring once again to FIG. 3, a known RAIL architecture provides a useful environment for employing the present invention. The invention may also be employed in a single library without the combination of redundant libraries. Media storage unit 86 in library 92 houses a plurality of data mediums. Recall that in the context of this invention disclosure, a volume is considered synonymous with a data medium. The volume 81a contains user data for which parity must be created to enable data recovery following an error. The volume 81a is accessible for automatic mounting in any of drives 64-67 by the robotic picker 70. In a similar fashion, the picker 71 in the library 94 may access the volume 83d for mounting in any of drives 68-74. The volume 83d contains user data for which parity must be created in order to enable data recovery. The inventor has recognized that the most likely candidate for failure in any of libraries 92, 94, and 96 is a respective robotic picker belonging to that library, so the invention employs a method to take advantage of this critical recognition. For example, since the volume 81a is served by the picker 70 in the library 92, and the volume 83d is served by the picker 71 in the library 94, the invention enables the employment of a third volume 85b designated as a parity volume in the library 96. Parity data related to the volumes 81a and 83d is stored on the parity volume 85b. In this example, the data volumes 81a and 83d, and the parity volume 85, form a redundancy group denominated for the purposes of this disclosure as a "parity group". By spreading members of a parity group among multiple libraries, the present invention enables recreating data stored in a library that is not in service due to a picker failure. For example if picker 70 fails, parity volume 85b served by picker and data volume 83d served by picker 70 can be used to recreate the data stored on volume 81a.
When a data volume, such as volume 81a, is written the control logic 58 writes a message to log file 63a stored on permanent storage unit 63 to indicate that a particular range of data has been updated on the volume. The log file 63a serves to indicate to control logic 58a that parity for data stored in an address range marked as updated is no longer valid, since the parity was written before the data in the indicated range had been updated.
An important aspect for implementing the present invention is a choice of alternative embodiments for scheduling when parity is written. One scheduling embodiment involves a method of building parity "intermittently", when a predetermined event occurs, such as inactivity of the control unit 62. Another scheduling embodiment is "building all parity at one time", such as upon export of a parity group from a storage unit, such as unit 86, to a location outside of the library, such as outside of library 92 to remote storage (not shown). In either embodiment, intermittent parity building or building all parity at one time, it is necessary to mount each volume belonging to a parity group on a drive so that it may be read or written. This may be accomplished automatically by control unit 62 commanding a picker, such as picker 70, through logic 58 and further by controlling the operation of drives in the respective library, such as drives 64-67.
In one embodiment, the present invention is implemented with a method for building all of the parity data at one time. One example of a convenient time to build all of the parity data is upon exporting the volumes that comprise a parity group to a location outside of the library. This is particularly advantageous in a single library environment, such as library 92, not combined with 94 and 96, because storage space is likely to be limited in a single library. A common practice is to send volumes out of the library that have not been changed in a long while to free up storage bins. Another example is building parity for a parity group that will remain in its respective library. This is a more convenient technique to employ in the case of multiple libraries which form a RAIL environment, such as the case with the existence of libraries 92, 94, and 96. In either environment, parity is created after a host 60 update to a data volume by calculating parity for the entire range of sectors contained on the volume, irrespective of which ranges have been updated. The advantage of this technique is that on a periodic basis, such as every night at 3 a.m., parity is updated and there is no need to maintain a log file of changes, such as log file 63a. A further advantage is that a larger range of data can be written at one time, than allowed with intermittent updating, which only allows writing of parity for those ranges which have changed. Additionally, a parity-- control-- block, such as block 106, indicating which sector ranges are pre-erased allows for very fast writing of parity because the control logic 58 can simply avoid reading or writing data stored in pre-erased sectors.
Referring to FIGS. 5 and 3, a flow chart showing a method for building all parity at one time in at least one automatic storage library is shown. The method is preferably implemented by control logic 58 in control unit 62, although it could be implemented in hardware or as microcode in a suitable microprocessor (not shown). It is envisioned that control logic 58 may be best implemented in the known C programming language with reference to the flow chart logic for purposes of coding the program. In step 130, the process is started wherein a parity group is created shown as the pseudo code statement "make-- parity-- group". A parity group is created by control logic 50 which reads an input list that contains an entry for each data volume in the group, and a parity volume. Following the example from above, a parity group might include, volume 81a from library 92, volume 83d from library 94, and parity volume 85b from library 96. An abbreviated general way of stating the membership of a parity group is:
parity group i-j=(volume i, volume j, parity volume i-j).
In the exemplary case, parity group81 a-83d=(volume 81a, volume 83d, parity volume81a-83d), where parity volume81 a-83d=85b. Once the parity group is created, then each volume is physically mounted in a drive, such as drive 64, so that data may be read for creating parity, as shown in step 132. The mounting can occur synchronously in a serial fashion, as would be the case for a single library with a single robotic picker or asynchronously in parallel, as would be the case for a RAIL configuration. For example, this step is implemented by the control logic 58 issuing a command to a robotic picker 70, to physically mount the volume 81a in drive 64. This is a "physical mounting" of a volume for parity as opposed to a logical mounting. In an asychronous fashion, a simultaneous physical mounting of the other members of the parity group, volume 83d and parity volume 85b, by pickers 71 and 79 in drives 68 and 75 respectively, would also be commanded by control logic 58. A "mount for parity" refers to a mapping of free space from a volume mounted in a physical drive, and must follow a physical mounting. The free space refers to data blocks on a volume that have pre-erased sectors and also to data blocks that have unallocated written sectors. The mount for parity step, shown as a pseudo code statement "mount-- for-- parity", in step 134, is a routine implemented by control logic 58. The mount-- for-- parity routine, in a preferred embodiment, derives an independent map 61a of free space for each volume (81a, 83d, and 85b) in the parity group. In a multitasking environment, an independent operation of the mount-- for-- parity routine for each volume in the parity group can run simultaneously in an asynchronous fashion.
Referring to FIG. 7, the mount-- for-- parity routine invoked in 134 of FIG. 6 is shown in more detail. For ease of explanation, the exemplary case of volume 81a in library 92 being operated on by logic 58 for the purposes of mount-- for-- parity is assumed; however, it should be understood that the steps explained below apply to the general case of any data volume belonging to a parity group. In step 156, the mount-- for-- parity step begins in the general case by being passed the volume name. In the exemplary case, the volume name equates to an identifier for volume 81a. Each volume in the parity group can be operated on asynchronously as shown in step 158. In step 160, control logic 58 writes to parity-- control-- block 106 of volume 81a. The parity-- control-- block 106 is not striped for parity, rather it is used for controlling the parity operation. The parity-- control-- block 106 contains a list of the data volumes and parity volumes in the parity group, the list being denominated as the "list-- of-- volumes-- in-- group". This list can be used to determine the members of a parity group which can be helpful for error recovery purposes. Additionally the parity-- control-- block also contains a flag for indicating the state of data on the volume, the flag being denominated as a "consistency-- flag". The consistency-- flag may either indicate "true" or "false", either of which may be arbitrarily represented by a "1" or a "0". For example, a "false" consistency flag would indicate that data has been updated on the volume 81a, but parity has not yet been recalculated to reflect the update. The consistency flag may be used for error recovery, for example in a scenario where library 92 is taken out of service after data is updated on volume 81a, but prior to recalculating the parity.
Referring again to FIGS. 7, 3, and 4b, the free space map 61a indexing sectors which are pre-erased is built by control logic 58, in order to allow parity to be calculated for magneto-optical disks to be built without inducing errors. Additionally, the map 61a stored in controller electronic memory 61 includes mapping information for space which is written but unallocated, for example, as in the case of a file which has been marked as erased but not yet physically removed from the volume. Thus, in step 162 the control logic 58 reads the free space information in the freespace file in block 114 on volume 81a in order to build the map 61a of pre-erased sectors which are standard on optical disks used in magneto-optical technology, and also to build a map of unallocated space on the volume. By building the map 61a of the free space information, the pre-erased sectors and unallocated written space can be skipped when data is read for parity because an arbitrary indicator, such as a "0" for each bit within a 1024 byte sector, will be placed in a buffer 61b in electronic memory 61 by logic 58, by executing a read-- for-- parity routine discussed in detail below. The parity information stored in the buffer 61b can be compressed to save space. The choice of a "0" is a logical choice for indicating free space; however, a "1" could be used instead as long as it is consistent with the parity calculation technique being used. Placing information derived from the free space map in the buffer 61b is an important step that is based on the inventor's critical recognition that the control logic must be informed of erased space, or time will be wasted calculating parity. Additionally, the calculating the parity using the information on the buffer derived from the free space map avoids a likely error scenario that would result if parity is calculated without mapping and placing information in the buffer. The freespace file in block 114 contains a directory of which blocks are written but unallocated, such as written free space block 112, and of those blocks containing one or more sectors of pre-erased free space, such as block 120. For the sake of simplicity, the FBA format shown in FIG. 4b shows only one block of written free space, but an actual data volume, such as volume 81a, would contain almost certainly a plurality of such blocks. As shown in step 162 of FIG. 7, after reading the freespace file in block 114, the control logic 58 builds the map 61a in the electronic memory 61 that defines which areas of the volume 81a contain pre-erased sectors and which are unallocated. In step 164, the map is stored in electronic memory 61 and is now available for use when the volume is read in order to calculate parity, the routine of reading being denominated as "read-- for-- parity". Finally, a "return" step 166 signals that the mount-- for-- parity routine is complete.
Referring once again to FIG. 5, after the mount-- for-- parity routine is complete, processing continues to step 136. In step 136, the control logic 58 sets a starting sector address for a range of data for which parity will be read. For example, if due to memory constraints, only 64 sectors can be read at a time (where each sector equals 1024 bytes), then control logic 58 should be programmed to set the starting address of sector 1, since the parity-- control-- block is preferably in sector 0. This means that the first range would go from sector 1 to sector 64. Thus, the first range could be denoted in shorthand fashion as range1 =(1, 64). In step 138, control logic 50 checks to see if the range for which parity will be built is the first range on the volume. If the answer to this inquiry is "yes", then a read-- for-- parity-- routine is implemented in step 142. The reason that the range is checked on the first pass is to set up a process where parity can be written for the previous range while data for parity is being read for the current range, as shown in step 140. Of course, this is not possible on the pass of the first range and this is why step 138 provides a branching step to 142 in the one instance of the first range being passed. In effect, parity data can be read for every volume in the parity group on a simultaneous and parallel basis and writing of parity can occur in a simultaneous and parallel basis to the read operation once the second range of data is passed into the iteration loop shown in steps 138-148.
Referring to FIGS. 5 and 8, the read-- for-- parity routine shown in step 142 of FIG. 5 is shown in more detail in FIG. 8. For ease of explanation, the exemplary case of volume 81a in library 92 being operated on for the purposes of mount-- for-- parity is assumed; however, it should be understood that the steps explained below apply to the general case of any data volume belonging to a parity group being read for parity. In step 168, the read-- for-- parity step begins in the general case by being passed the volume name and the range to be read. In the exemplary case, the volume name equates to a identifier for volume 81a, and the range refers to the first 64 sector range identified as (sector 1, sector 64) or simply (1, 64). In step 170, the control logic examines the map 61a built in the electronic memory 61 which contains free space information to determine if there is either written free space or pre-erased free space in the specified sector range. In the same step, the control logic writes a first set of data, preferably comprising O's, to the buffer 61b in the electronic memory 61 to indicate that identified sectors are free. In step 172, the remaining blocks in the range are read for parity and a second set of data which is a copy of the remaining blocks is stored in another buffer 61c in the electronic memory 61 by the control logic 58. Finally, a "return" step 174 signals that the read-- for-- parity routine is complete.
Referring once again to FIGS. 5 and 6, after the read-- for-- parity routine is complete, processing continues to step 144. In step 144, the control logic 58 calculates parity for the data that has been stored in the electronic memory 61 during the read-- for-- parity routine. Although the parity may be calculated in any manner, a common technique is to use an Exclusive Or or XOR operation. In step 146, the range is incremented. For example, the next range following the first range (1, 64), would be the second range (65, 129). In step 148, the range is tested to verify that it does not exceed the last sector address on the volume. If it does, then processing continues to continuation step 150 and no more parity is calculated. However, if the range does not exceed the last address on the volume then processing returns to step 138, and since in this case the range is no longer the first range, parity is written for the first range in step 140. Next, the read-- for-- parity routine is implemented for the second range by the control logic. The iteration loop is complete when all of the ranges are exhausted and processing continues to step 150. Finally, in step 152 (FIG. 6), each consistency-- flag for a volume which has had parity calculated following an update is set to "true". Processing ends in step 154, and the parity group may be physically exported to remote storage outside of the library if desired.
Reference is made again to FIG. 3 to explain another embodiment of the invention. In another embodiment, the invention is implemented with a method for building parity on an intermittent basis. Preferably, new parity data reflecting an update to data on a data volume is not created until the control unit 62 serving all three libraries 92, 94, and 96 is idle for a predetermined period of time. Although, waiting for the control unit to be idle is the preferred technique for minimizing decreased performance, other techniques are envisioned which would be within the spirit of the invention. For example, an algorithm could be employed to update parity groups on the basis of those containing volumes that had not been updated in a while according to a known least recently used (LRU) algorithm. In any case, once the predetermined triggering event occurs, the parity is written by control logic 58 which checks the log file 63a on permanent storage unit 63 to determine what range of data has changed on a data volume, such as data volume 81a. Once the range is determined, parity may be calculated for that range only, by mounting each volume in the respective parity group and calculating parity. It should be apparent to those skilled in the art, that keeping up with all changes and then recreating parity only when a sufficient period of inactivity has occurred in the library is more advantageous than the prior art RAID 3 architecture employed techniques which build parity every time there is an update to data on a data volume.
Referring to FIG. 9 an embodiment of the present invention employing a method for building parity intermittently is shown. The following flow chart is very similar to the flow chart shown in FIG. 5 and some steps, as noted, are identical to each other. This is because the primary differences between building intermittently and building all at once focuses upon the ranges for which parity is read and calculated. This is because building all parity data at once updates every range on the data volume at a predetermined time, such as a clock time (e.g., 3:00 a.m.) or a time designated as the time to export volumes from the library to a remote storage location. Whereas, building parity data intermittently only updates those ranges which have changed and at a time determined by some predetermined threshold of inactivity, such as an inactivity by control unit 62. Thus, steps 180, 182, and 184 are identical to previously-described steps 130, 132, and 134, respectively. In step 186, a list of ranges for which updates have been made is read, and the front range is extracted. For example, if the entries represent ranges in the list include the following entries, [(250, 314), (1, 64), (129, 193)], then the from range is (250, 314) because it is the first entry. In step 188, logic 58 checks to see if this is the first entry in the list. The objective of the inquiry is to determine if it is proper to write parity, i.e., at least one range has already been read for parity. Thus, if the answer to the inquiry is "yes" then parity is read for the current range which in the example is the range (250, 314). Step 190 is bypassed because the first entry is being operated on. The read-- for-- parity step 192 invokes the read-- for-- parity routine described in detail above in the description of FIG. 8. The read-- for-- parity routine is identical for either scheduling embodiment of the present invention. In step 194, parity is calculated for the current range in an identical fashion to previously described step 144 of FIG. 5. There is no analogous marking of the consistency flag step in the intermittent building embodiment because all ranges spanning an entire data volume is not being updated. In step 198, logic 58 checks to see if there are more entries in the list and if the answer to this inquiry is "yes" then processing begins again in step 186. In step 186 the next range is taken from the list. In the exemplary case the next front range is (1, 64). In step 188, if the inquiry to "is this the first entry in the list" is answered "no" then processing continues to 190. In step 190 parity is written for the previous entry range as described above. Processing then continues to step 192 in which case parity is read in an identical fashion as described above. Processing continues down through step 198 until there are no more entries in the list and then processing is done as shown in step 200.
Other embodiments and modifications of this invention may occur to those of ordinary skill in the art in view of these teachings. Therefore, this invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawing.
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|17 Sep 2013
|Commvault Systems, Inc.
|Systems and methods of media management, such as management of media to and from a media storage library, including removable media
|15 Jul 2013
|18 Feb 2014
|Commvault Systems, Inc.
|Systems and methods of media management, such as management of media to and from a media storage library, including removable media
|2 Sep 2008
|22 Apr 2014
|Commvault Systems, Inc.
|Parallel access virtual tape library and drives
|27 Dec 2012
|17 Jun 2014
|Commvault Systems, Inc.
|Systems and methods of media management, such as management of media to and from a media storage library
|16 Mar 2011
|9 Sep 2014
|Commvault Systems, Inc.
|Systems and methods of hierarchical storage management, such as global management of storage operations
|16 Sep 2013
|11 Nov 2014
|Commvault Systems, Inc.
|Systems and methods for uniquely identifying removable media by its manufacturing defects wherein defects includes bad memory or redundant cells or both
|21 Dec 2012
|30 Dec 2014
|Commvault Systems, Inc.
|Systems and methods of media management, such as management of media to and from a media storage library
|23 Dec 2013
|31 Mar 2015
|Commvault Systems, Inc.
|Parallel access virtual tape library and drives
|27 Dec 2012
|30 Jun 2015
|Commvault Systems, Inc.
|Restoration of centralized data storage manager, such as data storage manager in a hierarchical data storage system
|19 Sep 2014
|1 Dec 2015
|Commvault Systems, Inc.
|Systems and methods for performing storage operations in a computer network
|23 Sep 2011
|26 Jan 2016
|Commvault Systems, Inc.
|Data recovery operations, such as recovery from modified network data management protocol data
|26 Mar 2015
|2 Feb 2016
|Commvault Systems, Inc.
|System and method for sharing media in a computer network
|1 Aug 2014
|29 Nov 2016
|Commvault Systems, Inc.
|Methods and system of pooling storage devices
|6 Mar 2013
|27 Dec 2016
|Commvault Systems, Inc.
|Information management of mobile device data
|25 Jan 2016
|31 Jan 2017
|Commvault Systems, Inc.
|Data recovery operations, such as recovery from modified network data management protocol data
|14 Jun 2001
|27 Dec 2001
|Mcbryde Lee
|Data management architecture
|5 Aug 2002
|19 Dec 2002
|Santeler Paul A.
|Fault tolerant memory
|23 Nov 2001
|29 May 2003
|Parag Gokhale
|Method and system for scheduling media exports
|20 Aug 2002
|4 Sep 2003
|Moshe Yanai
|Remote data mirroring system having a remote link adapter
|27 Dec 2002
|15 Apr 2004
|Moshe Yanai
|Remote data mirroring
|7 Feb 2003
|2 Sep 2004
|Lo Hong-Jing (James)
|Method and system for managing optical storage medium file system structures
|15 Nov 2004
|11 Aug 2005
|Rajiv Kottomtharayil
|System and method for data storage and tracking
|30 Mar 2007
|27 Mar 2008
|Kochunni Jaidev O
|Systems and methods of media management, such as management of media to and from a media storage library, including removable media
|31 Mar 2008
|2 Oct 2008
|Parag Gokhale
|Systems and methods of media management, such as management of media to and from a media storage library
|30 Mar 2007
|2 Oct 2008
|Parag Gokhale
|Systems and methods of media management, such as management of media to and from a media storage library
|28 Mar 2008
|2 Oct 2008
|Rajiv Kottomtharayil
|Systems and methods of media management, such as management of media to and from a media storage library, including removable media
|31 Mar 2008
|9 Oct 2008
|Parag Gokhale
|Systems and methods of media management, such as management of media to and from a media storage library
|31 Mar 2008
|9 Oct 2008
|Muller Marcus S
|Systems and methods of media management, such as management of media to and from a media storage library
|28 Aug 2009
|17 Dec 2009
|Parag Gokhale
|System and method for extended media retention
|29 Dec 2009
|29 Apr 2010
|Rajiv Kottomtharayil
|Systems and methods of media management, such as management of media to and from a media storage library, including removable media
|17 Dec 2010
|14 Apr 2011
|Rajiv Kottomtharayil
|Systems and methods of media management, such as management of media to and from a media storage library, including removable media
|5 Sep 2012
|15 Aug 2013
|Yoshikazu Yamamoto
|Information storage medium library array apparatus, information recording method and information recording program
|10 Jun 1996
|5 Feb 1997
|Hewlett-Packard Company
|Online drive repair in a multiple drive library computer system
|10 Jun 1996
|25 Feb 1998
|Hewlett-Packard Company
|Online drive repair in a multiple drive library computer system
|17 Feb 1999
|6 Oct 1999
|Grau Software GmbH
|Method of storing data
|17 Feb 1999
|13 Oct 1999
|Grau Software GmbH
|Method of storing data
|26 Jul 2013
|31 May 2017
|Kabushiki Kaisha Toshiba
|Information recording apparatus, information playback apparatus, and formatting method
|U.S. Classification
|International Classification
|Cooperative Classification
|European Classification
|22 Sep 1994
Owner name: INTERNATIONAL BUSINESS MACHINES CORPORATION, NEW Y
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DEWEY, DOUGLAS WILLIAM;REEL/FRAME:007151/0671
Effective date: 19940907
|26 Dec 1995
|Certificate of correction
|24 Nov 1998
|Maintenance fee reminder mailed
|2 May 1999
|Lapse for failure to pay maintenance fees
|29 Jun 1999
|Expired due to failure to pay maintenance fee
Effective date: 19990502

subset: commoncrawl


text:
I was debating whether I should post this or not, but after finishing my first book I figured I might as well. This is by no means an indicator that I'll actually complete the challenge, but it's nice to get back to reading after all the craziness of the past few months.
2. Non US Author (mandatory!) - Three Daughters by Consuelo Saah Baehr
3. A book that was recommended by a blogger (mandatory!) - The Martian by Andy Weir recommended by Lisa
4. A book that has been on your TBR list for a year or more - The Goldfinch by Donna Tartt
5. A book with a kickass female character -
6. A book that is or will be a movie (or TV show) - The Perks of Being a Wallflower by Stephen Chbosky
7. A book written by a comedian or celebrity
8. A book with a one word title -
9. A suspenseful book -
10. A book about Summer -
As you can see, my list isn't complete yet so I would love some suggestions or recommendations if you've got any! I'll update as I go along.
What does your summer reading list look like?


text:
Majority of Tests for Horse Meat in Beef Products Negative28 March 2013
UK - Further test results from the first two phases of the Food Standars Agency's UK-wide sampling programme of beef products show 352 out of 362 samples were negative for the presence of both horse and pig DNA.
Of the remaining 10 samples, three were confirmed as containing pig DNA at or above the one per cent threshold. The three products were ASDA Spaghetti and Meatballs; ASDA Beef Cannelloni; and Apetito Beef Lasagne.
A further two, a Whitbread burger and IKEA meatballs, have now been confirmed as containing horse DNA at or above the one per cent threshold.
Both of these products have been previously reported by the food industry's own results and are already included in the table on the FSA's website.
The results of the last five samples are being challenged and awaiting the outcome of further independent tests.
If the products are found to be positive for contamination above the one per cent threshold, the results will be reported on the FSA website.
The purpose of the sampling programme is to get an accurate picture of the potential scale of contamination of beef products on high streets and in the catering supply chain across the UK.
The findings of the survey, carried out by 28 local authorities on behalf of the FSA, are consistent with those from the tests carried out by the food industry. The results confirm that the contamination and adulteration of beef products, with horse or pork meat, has been limited to a relatively small number of products.
The FSA's view remains that consumers should be able to trust what they see on food labels and the Agency is working with the local authorities where positive samples have been identified, with a view to taking enforcement action where necessary.
A total of 364 samples were originally taken as part of the survey. However, two samples failed to meet the criteria outlined in the sampling protocol and have therefore been discounted.
Enforcement officers followed a formal sampling protocol designed to ensure consistency across the 28 UK local authorities involved and the possibility of enforcement action where contamination was confirmed.
Each sample comprises three parts: one sent for testing by a Public Analyst; the second given to the food business where the sample was purchased and the remaining part is retained by the local authority in case of a dispute.
Where test results are disputed by the food business or manufacturer, the third sample may be sent for independent analysis by agreement between the local authority and the food business.
Further Reading
|Go to our previous news item on this story by clicking here.
TheMeatSite News Desk


text:
Even tho I work for Lowe's, I own a Ridgid 15"slide miter and a Ridgid portable stand. They are both ALMOST perfect. The miter saw will do any thing that i ask it to do. No complaints.(I build furniture as a hobby) The stand would be perfect if it would only extend a little futher out. When you need to cut an angle or a compound miter on a long board,it is real hard to hold it steady without adding a couple of extra stands out the infeed and outfeed of the table. Other than that I am happy with my Ridgid. I also Own a 12" Dewalt mitersaw. I use this for a backup saw.
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text:
The two teams will look to start their campaign in SAFF Championship on a winning note in order to not complicate their chances of progression into the next round…
The second match of Group 'B' fixture pits the two island nations against each other.
Maldives, ranked 153 in the world, are one of the contenders for the SAFF Championship title. They are the last team to have won the competition at the expense of holders India back in 2008.
All isn't well in the Maldives camp after manager Ibrahim Amir quit his post days before the tournament kicks-off in the wake of a bust-up between him and a few players.
Six teams have changed their coaches since the last edition of the SAFF Championships with only Afghanistan's Yousef Kargar and Maldives' Istvan Urbanyi managing to retain their jobs.
The Hungarian coach, in his second spell with Maldives, backed his side to put in a top performance at the tournament, which he believes they can win.
"The expectation is always highest, especially from the fans. We have a good team, but nobody can say that they have the strongest team. Small details will make a difference. We are ready to fight. Our target is to take back the trophy to make fans happy," he said.
They have been criticized in the past for being overly dependent on their skipper Ali Ashfaq. However if results in their three practice games prior to the tournament are to go by, it does seem that they finally seem to have a more competent attack than in the previous editions of SAFF.
They won against Dhiraagu Divehi League's Foreign XI 8-7 on penalties and thereafter embarked on a tour to Thailand where they downed Osotspa Saraburi 3-2 before going down with the same scoreline to Thailand U-19 side.
Sri Lanka, ranked 170 in the world along with hosts Nepal, travelled to Thailand to prepare for the SAFF Championship. They defeated Thailand's Division 2 champions Customs United SC and 2-0 with Chathura Gunarathna and Mohamed Sameer on the scoresheet. They lost their second game to a team from Hong Kong 5-1 and followed it up with a 2-1 victory over Thailand U21 side with goals from Mohamed Issadeen and Mohamed Nafeer.
In their final game, they downed Thailand Army side 3-0 with Mohamed Issadeen with D.M. Silva and Mohamed Fazal scoring the goals.
Following their disappointing exit from the group stages in the last edition of SAFFChampionship, Sri Lanka would be keen to erase those memories by putting in a strong performance in the opening match against Maldives.
The last time when the two sides met, Maldives thrashed Sri Lanka 5-1 to book a berth in the finals of the 2009 SAFF Championship. Ibrahim Fazeel and Ali Ashfaq starred in the triumph as they dispatched the Lankans with ease.
In the 17 matches between the two sides, Maldives have won 6, Sri Lanka have registered 3 wins, with 8 draws. It must be noted that Sri Lanka haven't beaten Maldives since their 1-0 victory in April, 2002.
Sri Lanka coach Claudio Roberto expressed confidence in his side and stated that his team are aware of the strengths and weaknesses in the Maldives squad.
"When we were in Thailand, Maldives were also there. We have got an idea of Maldives, and we are ready to face them."
How do you stay up with football when on the move? With http://m.goal.com –your best source for mobile coverage of the beautiful game.


text:
- Please select a date to see the proper prices!
- Meal can be requested on the spot
Best offer
31.30 € / person / night, no meal
Description of the accommodation:
Rooms, services The Elite Suites Pune is offering 39 nicely furnished rooms to stay in to those seeking accommodation in Pune. Car rental service is also available to help you discover all key highlights of the area. The exact scope of services offered by The Elite Suites Pune (including those for an extra fee) is available on the information sheet below.
Payment Credit card guarantee or advance bank card payment may be necessary for finalizing your reservation, depending on the exact room, date and price.
Arrival, opening hours The earliest check-in time is 12:00, the latest check-out time is 12:00. The personnel is at your service in English.
The Elite Suites Pune rooms Rooms
- Please select a date to see the proper prices!
Accommodation services
Car rental nearby


text:
Textile technicians maintain and repair machinery or plant used in textiles production. They may work in one or all of the following production areas within a textile factory, depending on its size:
Technicians check machines on a regular basis, fixing any minor problems. On modern machinery, computers assist technicians with diagnosing faults.
On locating a fault, they strip the machine, repair or replace the damaged parts, re-assemble the machine and then test it thoroughly before clearing it for production. Regular maintenance can involve cleaning, oiling, greasing and checking performance levels.
All work undertaken is recorded in detail.
Hours of work vary between 37 and 40 hours a week. This may involve a shift system and overtime may be available.
Most modern textile factories are light and spacious. Some manufacturing processes are noisy and the atmosphere can be hot and humid. Textile technicians wear protective clothing.
To be a textile technician you should:
Textile technicians can progress to specialised roles jobs such as quality control or research and development, or can move into supervision and management.
If you would like to know anything about Textile Technician that does not appear on Hotcourses, further information can be found below.


text:
Strong sales of the iPhone and iPad in have produced record earnings for the quarter ending 24 September, Apple announced yesterday (18 October). The company sold 17.07 million iPhones in the quarter, up 21% on the same period last year and 11.12 million iPads, a rise of 166% over the same quarter in 2010.
Revenues for Apple's fourth quarter reached $28.27bn ($20.34bn in 2010), while net profit for the quarter was $6.62bn, a rise of $2.31bn over the same quarter in 2010.
Apple CEO Tim Cook (pictured) said: 'We are thrilled with the very strong finish of an outstanding fiscal 2011, growing annual revenue to $108bn and growing earnings to $26bn. Customer response to the iPhone 4S has been fantastic, we have strong momentum going into the holiday season, and we remain really enthusiastic about our product pipeline.'
Despite disappointment in some quarters that Apple failed to produced an iPhone 5, the iPhone 4S has sold over four million units in the first three days since its release on 14 October.
The device is Apple's best selling device ever on release and caps an astonishing performance by the manufacturer this year. In the 12 months ending 24 September 2011 Apple's revenues were $108bn, a rise of $43bn on the previous year's figure of $65.2bn. Net profit reached $25.9bn, up from $14.0bn in 2010.
Apple's largest market is the Americas, where it earned $9.64bn in the quarter and shipped 1.7 million units (all products), followed by Europe with revenues of $7.39bn and 1.1 million units sold.
The iPhone and related products accounted for $10.9bn of the quarter's total turnover of $28.2bn, while the iPad brought in $6.86bn.
Apple CFO Peter Oppenheimer said: Looking ahead to the first fiscal quarter of 2012, which will span 14 weeks rather than 13, we expect revenue of about £37bn.'
Mobile Industry Awards 2017 - B2B & Distribution Finalists
Mobile Industry Awards 2017 – Retail Finalists announced
Mobile Industry Awards 2017 - Best Ruggedised Device
Nazish Dossa Joins Brighstar as UK Managing Director.
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Huawei - 'Our 2017 focus is premium products'
Retail Special
S6 to re-ignite the market
Brightstar 20:20 and HTC join forces
Meeting the challenge of in-building coverage


text:
GraphicRiver Cartoon Faces 6067229
Category: Stock Vector | Comment: ( 0 )
GraphicRiver Cartoon Faces 6067229
Stock Vector \ Characters \ Miscellaneous
Isolated \ Serious \ Suspicious \ Yelling \ Vector \ Illustration \ Happy \ Crazy
Stock Vector - Cartoon Faces 6067229 by memoangeles @ GraphicRiver
Stock Vector \ Characters \ Miscellaneous
Graphics Files Included: Vector EPS ; Layered: Yes ; Minimum Adobe CS Version: CS .
Cartoon faces with expressions clip art. Vector cartoon illustration. Each face on a separate layer. EPS 10 file included.
Cartoon Turtle; Brain Freeze; Cartoon Chicken; Weightlifting Brain; Warm and Cold Girls; Cartoon Astronaut; Happy Chicken.
Keywords: angry, cartoon, crazy, crying, emotion, expression, face, happy, illustration, isolated, sad, serious, suspicious, vector, yelling.
Download Link


text:
We send our members a full colour newsletter straight to their letterbox every 4 months with our most recent news and stories of our Danes.
Join us now!
Having behavioural problems?
At the moment you probably feel that the situation with your dog is irresolvable. However all behavioural problems can at least be managed and most can be completely cured. Even aggression. You may be thinking that your dog needs to live somewhere without another dog/without children/on a farm. These places don't exist and it is your responsibility to deal with your dog's problems, not someone else's.
If you have watched programmes like 'It's Me or the Dog' and 'The Dog Listener' you will have seen what seems like miracle cures and maybe thought that it cannot be true. However these programmes are not exaggerated, and if you can learn how to see things from your dogs point of view you can help your own dog and achieve a similar result. This is not to say that it will not require time and effort on your part - it most certainly will.
A good Canine Behaviourist will be able to quickly train you to resolve the behavioural problems you are experiencing with your dog. If you are prepared to put in the effort, you should seek advice and assistance from a qualified Canine Behaviourist in your area NOT a dog trainer. Select someone from the UK Registry of Canine Behaviourists or the Association of Pet Behaviour Counsellors. The cost is usually around £300
Does your dog deserve the financial commitment and time? Presumably you love your dog, so if you are not prepared to put in this sort of effort can you really expect someone who has not even met your dog to do it? Rescues should not be a dumping ground for lazy owners.
All that said, we never refuse to take in any Great Dane ( unless their quality of life has already been irreversibly compromised ) and we will not judge you if you decide to gift in your Dane. We are Great Dane experts and love our breed. The quality of care and rehabilitation that we provide is second to none, so if you have decided to part with your Dane please contact us rather than gift them to another rescue that cannot provide this standard of care and such a rigorous vetting procedure for potential new homes.


text: Dharwad District is an administrative district of the state of Karnataka in southern India. Dharwad is the cultural headquarters of North Karnataka. The administrative headquarters of the district is the town of Dharwad, also known as Dharwar. Dharwad is famous for its Dharwad Peda – a milk based sweetmeat. Dharwad is the administrative seat of the district of the same name. The municipality covers 191 km2. Dharwad is located 425 km north-west of Bangalore and 421 km south of Pune, on the main highway between Bangalore and Pune in Maharashtra. KREIS North Unit of National Projects Construction Corporation has its headquarters here. Karnataka High Court circuit Bench is also based here.


text:
Get CSB
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Dev Partners
Cloud Foundry Foundation
is an independent not-for-profit 501(c)6 Linux Foundation Collaborative Project. Our purpose is to make Cloud Foundry the leading application platform for cloud computing worldwide.
The Cloud Foundry Foundation exists to drive the global awareness and adoption of the Cloud Foundry open source project, to grow a vibrant community of contributors, and to create coherence in strategy and action across all member companies for the sake of the project.
We will do this by marketing the economic and technical activity of the entire Cloud Foundry community; governing with fairness, energy, and optimism; and growing a massive ecosystem based on application and skills portability.
Cloud Native Computing Foundation
features systems that are container packaged, dynamically managed and micro-services oriented--eases this process for developers and organizations alike by driving alignment among technologies and platforms.
The Cloud Native Computing Foundation will create and drive the adoption of a new set of common container technologies informed by technical merit and end user value, and inspired by Internet-scale computing.
The community will advance the state-of-the-art for building cloud native applications and services. Historically only a small number of companies who have been willing to make significant investments in development and operations have been able to benefit from this model of computing. It has been out of reach for the average developer. We aspire to make the same approach that solved challenging scalability and efficiency problems for internet companies available to all developers.
The Linux Foundation
protects and promotes the ideals of freedom and generous collaboration established through the development of Linux, and shares these ideals to power any endeavor aiming to make the future a better place in which to live.
By supporting the kernel development community and fostering collaboration on a truly massive scale, the Linux Foundation unites thousands of curious minds in the free and open exchange of ideas.
The Hyperledger Project
is a collaborative effort created to advance blockchain technology by identifying and addressing important features for a cross-industry open standard for distributed ledgers that can transform the way business transactions are conducted globally. The Project is a Linux Foundation Collaborative Project and implements many open source best practices familiar to other leading projects.


text:
Today we tried out our new Polydrons and little "X" asked me if I could build him a car. He had noticed that the new kit had wheels and as he loves cars, it was the most obvious request! The Polydrons are easy for little ones to click together but much harder for them to build 3D structures with.
Whilst I was working on his car we talked about the shape, length, where he wanted the windows, did he want the back open or covered. There was a lot of working together and sharing of ideas.
We made it in to a Safari truck to carry around all of the wild animals. "X's" other favourite toy! After making the back of the car closed, he decided that we needed the back open so he could put the animals inside.
After about half an hour, I offered to make pens for all of the animals using the Polydrons. As I made them, he filled them with family groups. Grouping all of the animals together. He talked about the mummy and daddy animals and the baby animals. Animals that were similar but with differences were friends, like the alligator and the crocodile.
- To provide little "X" with the different resources so that he can create the things that he imagines and extend his own play.
To continue to offer lots of opportunity for construction play and ensure there is a wide variety of open ended resources and loose parts for "X" to use in his imaginative play and small world play.
To offer the Polydrons again and help "X" to build simple 3D shapes such as cubes and pyramids.
Little "X" Showed a real interest in the Polydrons and added other items from the playroom to extend his enjoyment of them. He became engaged and focused in this open ended play and shared his ideas for the design of his car. He communicated them articulately and helped to re-think the design if we could not make it they way he wanted. He showed his own interests by asking for a car to be built and selecting the animals to be incorporated. He showed intense focus on this play activity for over half an hour. Motivated by his interests and enjoyment. He showed a well developed ability to group and sort, understanding of size and sequencing.
Today's play, meets the following EYFS Prime and specific areas
- Physical Development
- Expressive Art and Design
- Mathematics


text:
- New Year
New Year Stock Photos and IllustrationsView New Year Stock Videos
the products of the New Year category are presented here.
PIXTA's images are high quality and low price. Prices are based on the size of the image, starting at $5 per image.
All images are free of royalty charges, thus, they can be used multiple times, indefinitely.
Popular Images of New Year
This section introduces popular stock photos and illustrations in New Year category that have sold most.
PhotosMore New Year -themed photos
IllustrationsMore New Year -themed illustrations
Search items from popular categories of New Year
This section introduces popular categories and seasonal ones of New Year.


text:
HE advisors' conference
Where: Imperial College London, South Kensington Campus
Suitable for: Teachers, Heads of Sixth Form and HE Advisors
Date for 2017: 8 June 2017
Our HE advisors' conference is a free annual event, organised by our UK recruitment team.
It is designed to equip you with the information you need to be able to support your students' progression to university – particularly those who are considering applying to Imperial:
- attend talks by our Admissions Tutors
- visit our world-class facilities
- meet our recruitment advisors
- share best practice with colleagues working in the field
The HE advisors' conference is now fully booked. Please email Emma Ingle firstname.lastname@example.com to be added to the waiting list for this event.


text:
A Note About Our Sponsor
You may notice the ads strewn about the site for B&H Photo. I just wanted to take a moment to thank them for their support and recommend them to anyone who might be buying any kind of photo, video, lighting, or computer gear at all.
Before I moved to New York, and before the age of online shopping, I knew of B&H from the ads I had seen in the back of photo magazines. Based on their ads, I knew the place must be huge, but I imagined it as some kind of faceless warehouse in an industrial office park somewhere. The first time I went there in person, I was blown away. It was even bigger than I imagined, and it was like a camera wonderland. They had every piece of photo gear imaginable, right there in the store. The bizarre system of product elevators and conveyor belts that run along the ceiling and transport your purchases from the sales counters to the checkout area made the place seem like the store that Willy Wonka would have run if his passion had been photography instead of candy.
The sales people are knowledgeable and helpful, the customer service is excellent, the selection is unbeatable, and the so are the prices. They carry every piece of consumer and professional photo and video gear you could ever want, both on their website, and usually in stock in the store as well, and they have the best prices around. If I ever see an ad online for a price on camera gear that sounds too good to be true, just to make sure, I check out the B&H website to see how much that item really costs. If the advertised price is notably less than the B&H price, I know it's some kind of scam or bait-and-switch tactic, and a cursory look at some of that advertisers' online reviews confirms that this is the case.
If you are in the market for any kind of camera or electronics gear, consider clicking one of the B&H ads to the side or bottom of this page to find it. You can be confident that you're buying from a trustworthy source, and if you enjoy reading these blog posts, you'll be helping to support this site as well.