Hitachi ShadowImage for z/OS user guide (HIT9503-96004, June 2006)

ShadowImage for z/OS user guide 101
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Figure 51 Example of Using Consistency Group with FlashCopy(R) Mirror Version 2: Copying Data that is
Stored over Multiple Volumes
Figure 52 Example of Using Consistency Group with FlashCopy(R) Mirror Version 2: Copying Multiple
Data that are Stored over Multiple Volumes
Figure 51 illustrates the example of copying the data stored over the volumes #1-#3 to the volumes #4-#6.
You need to create pairs of volume #1 and #4, #2 and #5, and #3 and #6, then copy the data. However,
if the volume #1 is updated before the creation of the Pair B (pair of #2 and #5) completes, the
consistency of the data in the copy target cannot be maintained.
In, Figure 52, Data 2 in the volume #2 references Data 1 in the volume #1, and Data 3 in the volume #3
references Data 2 in the volume #2. Therefore, when you try to copy Data 1-3 to the volume #4-#6, if Data
1 is updated before the copying processing of Data 2 completes, consistency of copied Data 1 and
copied Data 2 cannot be maintained.
To prevent the abovementioned problems, FlashCopy Mirror Version 2 regards volumes #1-#3 as one
consistency group, and allows you to suspend the write operation from the host to the FlashCopy Mirror
Version 2 S-VOLs until the Pair A, Pair B, Pair C are all created and all the copying processing is finished.
To suspend the write operation from the host to FlashCopy Mirror Version 2 S-VOLs by using consistency
groups, you need to issue the pair creation command with an option parameter. For information about the
pair creation command and the option parameter, see ”TSO Command Supported by Compatible
Mirroring for IBM FlashCopy Version 2” on page 119. For the information about the example of using the
command, see ”Creating FlashCopy Mirror Version 2 Pairs: FCESTABL” on page 121.