HP P9000 for Compatible FlashCopy Mirroring User Guide (AV400-96388, October 2011)

Figure 5 Using consistency group with Compatible FlashCopy: copying data that is stored over
multiple volumes
Figure 6 Using consistency group with Compatible FlashCopy: copying multiple data that are stored
over multiple volumes
The first figure shows copying the data stored over volumes #1-#3 to volumes #4-#6. You need to
establish relationships of volume #1 and #4, #2 and #5, and #3 and #6, then copy the data.
However, if volume #1 is updated before the creation of the Relationship B (pair of #2 and #5)
is completed, the consistency of the data in the copy target cannot be maintained.
The second figure shows Data 2 in volume #2 references Data 1 in volume #1, and Data 3 in
volume #3 references Data 2 in volume #2. Therefore, when you try to copy Data 1-3 to volume
#4-#6, if Data 1 is updated before the copying processing of Data 2 is completed, the consistency
of copied Data 1 and copied Data 2 cannot be maintained.
To prevent the problems indicated above, Compatible FlashCopy regards volumes #1-#3 as one
consistency group, and allows you to suspend the write operation from the host to the Compatible
FlashCopy S-VOLs until Relationship A, Relationship B, and Relationship C are all created and all
the copying processing is finished. To suspend the write operation from the host to Compatible
FlashCopy S-VOLs by using consistency groups, you need to issue the pair creation command with
an option parameter.
When Compatible FlashCopy and Cnt Ac-S Z share volumes, the results of operations such as
creating pairs will differ according to whether you are using a consistency group or not.
This function can be used in Compatible FlashCopy SE.
Incremental FlashCopy function
Incremental FlashCopy maintains a relationship even after the copy operation from copy source
to target is completed. Later, when the S-VOL or T-VOL is updated, the updated data is managed
in a track as differential data. If the command to establish a relationship is re-executed on the
volumes originally related using the Incremental FlashCopy function, only differential data is copied.
Incremental FlashCopy function 11