Chapter 11. Advanced Copy Services 513
Migration offers the following options:
/SM590000Export to Image mode. By using this option, you can move storage from managed mode to 
image mode, which is useful if you are using the Storwize V7000 as a migration device. For 
example, vendor A’s product cannot communicate with vendor B’s product, but you must 
migrate data from vendor A to vendor B. By using Export to Image mode, you can migrate 
data by using Copy Services functions and then, return control to the native array while 
maintaining access to the hosts.
/SM590000Import to Image mode. By using this option, you can import a storage MDisk or LUN with 
its data from an external storage system without putting metadata on it so that the data 
remains intact. After you import it, all copy services functions can be used to migrate the 
storage to other locations while the data remains accessible to your hosts. 
/SM590000Volume migration by using volume mirroring and then by using Split into New Volume. By 
using this option, you can use the available RAID 1 functions. You create two copies of 
data that initially has a set relationship (one volume with two copies, one primary and one 
secondary) but then break the relationship (two volumes, both primary and no relationship 
between them) to make them independent copies of data. 
You can use this option to migrate data between storage pools and devices. You might use 
this option if you want to move volumes to multiple storage pools. Each volume can have 
two copies at a time, which means that you can add only one copy to the original volume, 
and then you must split those copies to create another copy of the volume.
/SM590000Volume migration by using move to another pool. By using this option, you can move any 
volume between storage pools without any interruption to the host access. This option is a 
quicker version of the Volume Mirroring and Split into New Volume option. You might use 
this option if you want to move volumes in a single step, or you do not have a volume 
mirror copy.
With Volume mirroring, you can move data to different MDisks within the same storage pool or 
move data between different storage pools. Using Volume mirroring over Volume migration is 
beneficial because with Volume mirroring, storage pools do not need to have the same extent 
size as is the case with Volume migration.
Starting with V7.3 and the introduction of the new cache architecture, mirrored volume 
performance was significantly improved. Now, lower cache is beneath the volume mirroring 
layer, which means that both copies have their own cache.
This approach helps when you have copies of different types, for example generic and 
compressed, because now both copies use its independent cache and performs its own read 
prefetch. Destaging of the cache can now be done independently for each copy, so one copy 
does not affect performance of a second copy. 
Also, because the IBM Storwize destage algorithm is MDisk aware, it can tune or adapt the 
destaging process, depending on mdisk type and usage, for each copy independently.
Migration: Although these migration methods do not disrupt access, you must take a brief 
outage to install the host drivers for your Storwize V7000 if you do not already have them 
installed. 
Note: Volume mirroring does not create a second volume before you split copies. Volume 
mirroring adds a second copy of the data under the same volume. Therefore, you end up 
having one volume presented to the host with two copies of data that are connected to this 
volume. Only splitting copies creates another volume, and then both volumes have only 
one copy of the data.