HP StorageWorks XP24000 for FlashCopy Mirroring Software User's Guide (T5240-96001, June 2007)

Consistency Group
1
2 3
4
5 6
Data 1
Data 3
Data 2
Reference Reference
Relationship A
Relationship B
Relationship C
Figure 18 Example of Using a Consis ten cy G roup with Version 2: C o pying Multiple
Da ta t hat is Stored over Multiple Volumes
Figure 17 on p a ge 46 illustrates an example of copying data stored over volumes #1 through #3 to
volumes #4 through #6. You need to establish relationships between volume #1 and #4, #2 and #5, and
#3 and
#6, and then copy the d ata. However, if volume #1 is updated before the creation of Relationship
B
(pair of #2 and #5) is completed, the consistency of the data in the copy target cannot be maintained.
In Figure 18 on page 47, 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 through 3 to volumes #4
through #6, if Data 1 is updated before the copying processing of D ata 2 is completed, the consistency
of copied Data 1 a nd copied D ata 2 cannot be maintained.
To prevent the above-mentioned problems, Version 2 regards volumes #1 through #3 as one
consistency group, and allows you to suspend the write operation from the host to the Version 2
S-VOLs until Relationship A, Relationship B, and Relationship C are all created and all the copying
processing is nished. To suspend the write operation from the host to Version 2 S-VOLs by using
consistency groups, you need to issue the pair creation command with an option parameter.
For information abo ut the relationship establishment comm and and the option parameter, see
Establishing Version 2 Relationships on page 76.
Note:
When Version 2 and TrueCopy for Mainframe share volumes, the results of operations such as
cre a ting pairs will differ according to whether you are using a consistency group or not. For details,
see Using Version 2 with TrueCopy for Mainframe”onpage50.
Releasing Version 2 Relationships
You ne
ed to issueTSOs FCWITHDR command to releasea Version2 relationship. Note thatthere is no
DFSMSdss command for releasing a Version 2 relationship.
If the following operation or processing is executed, the FCWITHDR command may be issued
automatically by a host server and relationships may be deleted.
Ause
r
deletes a dataset.
Auser initializes avolume.
A temporary dataset is deleted when a job completes.
Intero perability With O ther P roducts and Functions
The following table shows whether you can or cannot share Version 2 volumes with the volumes of
other
storage system co py solutions.
XP24000 for FlashCopy Mirroring Software User's Guide
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