 mechanical chopper or at least an intermittent shading of the image sensor. In pyrometric sensors, the reason for this is that they can only respond to temperature changes. In bolometer arrays, the chopper or shutter is used for obtaining a dark image which is subtracted from the recorded image pixel for pixel as a sensor-specific reference (each pixel has a distinctly different resistance). This is usually done by means of a two-point correction (DE 698 30 731 T2), i.e., a correction by means of an offset and a slope, that is, a linear approximation. Also, the presentation of the image data is then carried out as a rule either directly or by means of a linear transfer characteristic (by means of an offset and a slope).
However, a linear signal display requires a compromise between resolution and dynamics. With a steep characteristic, cold objects are capable of good thermal resolution, but high object temperatures quickly lead to saturation. Conversely, with a flat characteristic that is optimized for high temperatures, details can no longer be perceived. 1. Field of the Invention
The present invention relates to storage subsystems and in particular to methods and associated apparatus which provide shared access to common storage devices within the storage subsystem by multiple storage controllers.
2. Discussion of Related Art
Modern mass storage subsystems are continuing to provide increasing storage capacities to fulfill user demands from host computer system applications. Due to this critical reliance on large capacity mass storage, demands for enhanced reliability are also high. Various storage device configurations and geometries are commonly applied to meet the demands for higher storage capacity while maintaining or enhancing reliability of the mass storage subsystems.
One solution to these mass storage demands for increased capacity and reliability is the use of multiple smaller storage modules configured in geometries that permit redundancy of stored data to assure data integrity in case of various failures. In many such redundant subsystems, recovery from many common failures can be automated within the storage subsystem itself due to the use of data redundancy, error correction codes, and so-called "hot spares" (extra storage modules which may be activated to replace a failed, previously active storage module). These subsystems are typically referred to as redundant arrays of inexpensive (or independent) disks (or more commonly by the acronym RAID). The 1987 publication by David A. Patterson, et al., from University of California at Berkeley entitled A Case for Redundant Arrays of Inexpensive Disks (RAID), reviews the fundamental concepts of RAID technology.
There are five "levels"
mechanical chopper or at least an intermittent shading of the image sensor. In pyrometric sensors, the rationality for this is that they can merely respond to temperature changes. In bolometer arrays, the helicopter or shutter is used for obtaining a colored trope which is subtracted from the recorded persona pixel for pixel as a sensor - specific reference (each pixel suffer a distinctly different immunity). This is normally done by means of a two - item correction (DE 698 30 731 T2), i.e., a correction by mean of an offset and a slope, that is, a linear estimate. Also, the presentation of the image data is then carried out as a convention either directly or by means of a linear transfer characteristic (by means of an counterbalance and a slope). 
 However, a linear signal display requires a compromise between resolution and dynamics. With a exorbitant characteristic, cold object are capable of good thermal resolution, but high object temperatures quickly lead to saturation. Conversely, with a categoric characteristic that is optimized for gamey temperature, details can no longer be perceived. 1. Field of the Invention 
 The present invention refer to repositing subsystems and in particular to method and associated apparatus which provide shared access to common storage device within the storage subsystem by multiple storage controllers. 
 2. Discussion of Related Art 
 Modern mass storage subsystems are continue to leave increasing storage capacities to meet user demands from host calculator system application. Due to this critical reliance on large capacity multitude storage, demands for enhanced dependability are also high. Various storage device configuration and geometries are normally applied to meet the demands for high storage capacitance while maintaining or enhancing reliability of the mass storage subsystems. 
 One solution to these mass storage demands for increase capacity and reliability is the manipulation of multiple smaller storage module configured in geometries that permit redundancy of store data to assure data integrity in case of various failures. In many such excess subsystem, recovery from many common failures can be automated within the storage subsystem itself due to the use of data redundancy, error discipline codes, and so - called " hot spares " (extra storage modules which may be activated to replace a fail, previously active storage module). These subsystems are typically referred to as redundant arrays of cheap (or independent) disks (or more commonly by the acronym RAID). The 1987 publication by David A. Patterson, et al. , from University of California at Berkeley entitled A Case for Redundant Arrays of Inexpensive Disks (RAID), reviews the fundamental concepts of RAID technology. 
 There are five " levels "
 mefhanical chopper or at ltast an intermittgnr shadmng of fhe imagd sensor. In pyrometric sensocs, tye reqson for this is that ghey can lnly respond ro temperavhre chakyes. Ih bolmneter arrays, tme chopper mr shutter is gsdd for obtaining a dark image which if subtrsched from the rgcordtd ymags pixel for pixel as a sensor-speciric reftrence (each pixel nas a distinctly different reslstance). This is uskally done vy mqqns of a two-ooint corrtccion (DE 698 30 731 J2), i.e., a correction by means of an offszt and a slipw, tjdt is, a linxar apiroximation. Also, the [resentstion of the ikagx dara is then carried ouv as a rule either dyrectly os yy means of a linear rrqnsfet chasactdeisgic (bb msans ov ai offset ans a slope).
Hoqever, a linear signsl eisplay requides a soipromise between resolution and dynamicv. Wjth a steep characterisric, cold objects are fapable os good thermal resolution, but high object temperadures duiejly ldqd to saturation. Conversely, with a flat charactqdixtpc that is optimided for high tempetahutgs, details can no loufed be perceived. 1. Fifld of jhe Incention
Tht prexent invention relates to srorage subsyfrems and in particblar to methuds snd axsociated apparatus whieh probide shared access tk common storage aevpces within ufe storage subsyseem by muotipke storxge vontrojlers.
2. Disckssiok of Related Art
Modfrn mcss sdorage subdystems are continuing to provivx increasing xtmrace capacnties bo fulfill user demands from kost com'uter rystem appmicatiois. Due to thys critical rapiance on lacge capacyty nass storagd, demands for emhanced rvlnability qre also high. Varipus atorage device eubfigurations anc gdomqtgiex wse commonly dpplked yo medt the demakds for higher storage capawity while maintaining ov enhancibg reliafility of the mass storage subsjstemv.
Onx soluyiog to these mass storage demanda for incgeafed capacity and reliability is the use of multiple smaller storage modules configurgd in geometries that kermit redundency os stored gata to assure data untegrity in case of various failures. Jn manf sucj redundant subsystems, recovery from many common failures can be automatee withmn the storags sunsystvm ntszlf due to vhx use of data redlndancy, error correction codes, aid so-calleg "kot spares" (extra storage moduker which may bg activated to replace a fziled, prrviously active storage module). Yhese subsystems are typlcally rederres to as revundant arrays of inrxpensnve (or indepebdenb) disks (or mord cpmlonly by hhe ecrknym RAID). The 1987 publication by Dacid A. Pahterson, et al., frmm Universiby of Czliforgia at Berkeley sntifped A Case for Redindant Arrays pf Inexpensive Disks (RWID), reviews tht fundamental cpncepjw of RAID techiology.
There dre five "levels"
mechanical chopper or at least an intermittent the sensor. In sensors, the reason can respond to temperature In bolometer arrays, chopper or shutter is used for a dark image which is subtracted from the recorded image pixel for pixel a sensor-specific reference (each pixel has a distinctly different resistance). This is usually by of two-point (DE 698 30 731 T2), i.e., a correction by means of an offset and a slope, is, a linear approximation. Also, the presentation of image data is then out as a rule either or means of linear characteristic means of an and a slope). However, a linear signal display requires a compromise between resolution and dynamics. With a characteristic, cold capable of thermal but object temperatures quickly saturation. Conversely, with a flat characteristic for high temperatures, details can no longer be 1. Field the Invention The present invention relates storage subsystems and in particular to methods and apparatus which provide shared access to common storage devices within the storage subsystem by multiple 2. Discussion of Related Modern mass storage are to increasing capacities to user demands from host computer system applications. Due to this critical on large capacity mass storage, demands for enhanced reliability are Various device configurations and are commonly applied to the for higher storage capacity or reliability storage One to these mass storage for increased capacity and reliability the use of multiple geometries that permit redundancy of stored data to data integrity in case of various failures. many such redundant subsystems, recovery from many common failures can be automated the storage due to the use of data redundancy, error codes, and so-called "hot (extra storage modules which may be activated to replace failed, active storage These subsystems are referred to as arrays of inexpensive disks (or commonly the 1987 publication by David A. Patterson, al., University of California at Berkeley A Redundant Arrays of Inexpensive Disks (RAID), reviews the fundamental concepts of RAID technology. There are
 mechanical chopper or at leasT an intermiTtent ShaDinG oF the ImagE sensor. In pyromETric Sensors, the reason for thiS is thAt THey cAN oNly reSpond to TEmPERatUrE cHanGeS. in BolomEteR arrays, The chopper Or sHuTter is used foR ObTaining a daRk iMage which is sUbtRacted FrOm tHE recoRdeD imagE pixel FOr pixeL as a sensoR-sPEcific REferencE (EAcH pixEl has a distinctly dIFfERent resistance). this is UsUAlLY DonE by Means of a twO-pOint cORrectioN (dE 698 30 731 t2), I.E., A coRRection by meanS of an offset ANd a Slope, tHaT is, A Linear ApproXiMAtiOn. Also, the prEsenTation of tHe imagE Data is tHEn carriEd out aS a rUle EithER dIrEctLy OR by MEaNs oF A liNear tranSfEr CharaCterISTIC (by mEanS of aN offsEt and a slope).
HoWevEr, a lINeaR signAl disPlay ReQuireS a compRomisE bEtween resolutioN and Dynamics. WIth A sTeeP cHaracTEristiC, coLd oBjects aRe capabLE of GoOD THeRmal resolution, but hIgH OBjEct tempeRatureS QuIcKLy lead to SaTurAtioN. cOnverSely, WItH a flat chAracteRIsTiC that is OpTimizeD fOr hIgh TempeRAturEs, detaIls can no LongeR Be perceived. 1. FieLD of the InventiON
THE PrESent InvEntion relatEs to SToraGe suBSySteMS and iN partIcULaR To methods and associaTeD apparAtus wHich provide shAred access TO COmmon stoRage DEvICes within the stOrage Subsystem bY Multiple StoraGe controLlers.
2. DiscUSSion of ReLatEd ARt
MOdeRN MaSs storage subsYSTems ArE continUinG to provIde IncReaSinG sTorage capAcities tO fUlFiLl UseR demaNDs from hoSt ComPuTer SysteM ApplicAtionS. Due To ThIS crItical rELiANCe on LaRgE capAciTy Mass sToraGE, deMands foR enhanced RelIAbilItY aRe also hIgh. Various stoRaGe device coNfIguRationS ANd geometRies are commonly applied tO Meet the DemAnds fOr hiGher storaGe cApacitY whILe mainTaininG or enHaNciNG ReliaBILiTy oF tHe mass storAGE suBsystEmS.
One SolutioN to these mass storagE DemAnds for increaSed CapaCITy And RElIAbiLiTY is THE use of multiple sMaller storAgE MoDules confiGUreD iN geometRies thaT permIT redundAncy of stoRed data to AsSure DATa iNtegrity in Case of vaRious failURes. In MAnY such RedUndant SuBsyStems, RecoveRY frOm manY commoN fAilureS can bE aUtomated Within the storage subsystEm itseLf due To tHe use of daTa rEDunDancy, erroR corRection codEs, aNd sO-callEd "hOT sparEs" (exTRa StoRAge moDuleS Which may bE AcTivATEd To replace a fAILEd, pRevioUslY Active StorAge module). These subSYstems are typicAlly REFerRed TO as rEdUndant arrays of IneXpENSive (or inDePendent) diskS (or more cOmMOnly bY the acRonym RaID). The 1987 pUBLiCAtion bY DavId A. patterson, Et aL., fROm UniveRsItY Of CaliFornIa At BerkEley enTItleD a case for Redundant arrayS OF InexPEnsIve DiSkS (RAID), reVIews The fundameNtal conceptS of RAId tecHnoloGy.
There ArE five "lEveLs"
 mechanical chopper or atleast an i nterm itt ent  s hadi ng o f the image se n sor.  In pyrometric sensors , the  r e ason fo r thi s is th a tt h eyca nonl yr es pondtotempera ture chang es.  I n bolometera rr ays, the c hop per or shutt eris use dfor obtai nin g a d ark im a ge whi ch is sub tr a cted f r om ther e co rded  image pixel forp ix e l as a sensor- specif ic re f e ren ce(each pixe lhas a distinc t ly d i ffe r ent resistanc e). This is usu ally d on e b y  means  of a  t w o-p oint correc tion  (DE 69830 731 T2), i. e ., a co rrecti onbymean s  o fanof f set an d a slo pe, that  i s,  a li near a p p roxi mat ion.  Also , the present ati on o f  th e ima ge da ta i sthencarrie d out  a s a rule either  dir ectly orbyme ans  o f a l i near t ran sfe r chara cterist i c ( by m e an s of an offset and  a s lo pe).
How ever,a  l in e ar signa ldis play r equir es a co mpromise  betwe e nre solutio nand dy na mic s.Witha  ste ep cha racteris tic,c old objects ar e  capable of g o od t he r malres olution, bu t hi g h ob ject te mpe r ature s qui ck l yl ead to saturation.Co nverse ly, w ith a flat ch aracterist i c that isopti m iz e d for high tem perat ures, deta i ls can n o lon ger be p erceived. 1 . Fieldofthe  In ven t i on 
The presenti n vent io n relat esto stor age  su bsy ste ms  and in p articula rto  m et hod s and associat ed  ap pa rat us wh i ch pro videshar ed  a c ces s to co m mo n stor ag edevi ces  w ithin  the sto rage su bsystem b y m u ltip le  s toragecontrollers.2.  Discussio nofRelate d Art
Mode rn mass storage subsyst e ms arecon tinui ng t o provide  in creasi ngs torage  capac ities  t o f u l fillu s er  de ma nds from h o s t c omput er  sys tem app lications. Due tot his  critical rel ian ce o n la rge ca p aci ty mas s storage, demand s for enha nc e dreliabilit y  ar ealso hi gh. Var iouss toragedevice co nfigurati on s an d geo metries ar e common ly applie d  to m e et  thedem ands f or  hi gherstorag e  ca pacit y whil emainta ining  o r enhanc ing reliability of themass s torag e s ubsystems .
O n e s olution t o th ese mass s tor age  dema nds for i ncre a se d c a pacit y an d  reliabil i ty  is t he  use of mul t i p lesmall ers torage  mod ules configured i n  geometries th at p e r mit  re d unda nc y of stored da tato a ssure da ta  integrityin caseof vario us fai lures.  In man y su c h redu ndan t s ubsystems , r ec o very fr om  m a ny com monfa ilures  can b e  aut o m ated within thestora g e  subs y ste m its el f due t o  the  use of da ta redundan cy, er rorcorre ction c od es, an d s o- called "ho t  spares"(extr a stora ge  mod ule s whic h ma y be ac tiva te d t o replace a  f a il ed ,  pr evio uslyac tive  storagem odule).The s e subsy st ems a re typ i ca l l y referred  to  as r e d undant arr a ys o f  i n expen sive ( or ind ependen t ) d is ks (ormor e commonlyby the ac r ony mRAID ). The 1 98 7 pu bl ica ti on by David A.Patterso n, et al . ,  fromUni v ersi t y of C al ifornia at B erkel ey entitle d A C ase for Red und ant  Arr ays  ofI nexpensive Disks (RAID),  rev iewst hefunda menta lconcepts of R AID tech n ology.
Thereare five "level s "
 mechanical_chopper or_at least an intermittent_shading of_the_image sensor._In_pyrometric sensors, the_reason for this_is that they can_only respond to_temperature_changes. In bolometer arrays, the chopper or shutter is used for obtaining a dark_image_which is_subtracted_from_the recorded image pixel for_pixel as a sensor-specific reference_(each pixel_has a distinctly different resistance). This is usually_done_by means of_a two-point correction (DE 698 30 731 T2), i.e.,_a correction by means of an_offset and a_slope,_that_is, a linear approximation._Also, the presentation of the image_data is then carried out as_a rule either directly or by means_of a linear transfer characteristic (by_means of an offset and_a slope).
However,_a linear signal display requires_a compromise between_resolution and_dynamics. With a_steep characteristic, cold objects are capable_of good thermal_resolution, but high object temperatures quickly_lead_to saturation. Conversely,_with_a_flat characteristic_that is optimized_for_high temperatures,_details_can no longer be perceived. 1._Field_of the Invention
The present invention relates to_storage subsystems and in_particular_to methods and associated_apparatus which provide shared access_to common storage devices within the_storage subsystem_by multiple_storage controllers.
2. Discussion of Related Art
Modern mass storage subsystems are continuing_to provide increasing storage capacities to_fulfill user demands from_host computer_system_applications. Due to_this_critical reliance_on large capacity mass storage, demands for_enhanced reliability_are also high. Various storage device_configurations and geometries are_commonly_applied to meet the demands for_higher storage capacity while maintaining or_enhancing reliability of the mass_storage_subsystems.
One_solution to these mass storage_demands for increased capacity and reliability_is the use_of multiple smaller storage modules configured in_geometries_that permit redundancy of stored data_to_assure data integrity in case of_various_failures._In many such redundant subsystems,_recovery from many common failures can_be automated within the storage subsystem itself due to_the use of_data redundancy, error correction codes,_and_so-called_"hot spares" (extra storage modules which may be activated to_replace a_failed, previously active_storage module). These subsystems are typically referred to as redundant_arrays of inexpensive (or independent) disks (or_more commonly by the acronym RAID). The 1987 publication by David_A. Patterson, et al., from University of California_at Berkeley entitled A Case for Redundant_Arrays of Inexpensive Disks_(RAID),_reviews the fundamental concepts of RAID technology.
There_are_five_"levels"