HP XP Racks - Manual (Page 26)

Figure notes:
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RAID Manager manages the consistency group on all primary and secondary system. Business
Continuity Manager cannot be used with multiple systems.
•
Open and mainframe primary volumes (P-VOLs/P-VOLs) receive I/O requests from their
applications at the primary (main) site, and data in the volumes is updated.
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Continuous Access Synchronous or Continuous Access Synchronous Z runs the copy operation
in the consistency group.
•
When the open or mainframe host system guarantees the update order, then data consistency
in P-VOLs and S-VOLs is insured. When the host system does not guarantee update order,
data consistency is not insured.
Consistency group requirements
Requirements are provided for the following consistency group (CTG) configurations.
•
“Consistency group for pairs in one primary and one secondary XP7” (page 24)
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“Consistency group for pairs in multiple primary and secondary systems” (page 25)
Requirements for a CTG for one primary and one secondary system
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A consistency group is configured on the primary and secondary system.
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A maximum of 8,192 pairs can be assigned to a consistency group. (For consistency group
127, the maximum is 4,096 pairs.)
•
A maximum of 256 consistency groups can be assigned to one primary and one secondary
system.
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Assign a consistency group number in a range from 00-FF. The number must be unused.
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When you have multiple pairs in the same consistency group, they must exist between the
same primary and secondary system.
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A pair can be assigned to one consistency group only.
•
Continuous Access Synchronous pairs can be in the same consistency group as Continuous
Access Synchronous Z pairs. Use the same consistency group number for both types.
•
When assigning pair volumes that belong to a virtual storage machine to a consistency group
consisting of one primary and one secondary system, all the P-VOLs in the consistency group
must belong to the same virtual storage machine.
•
If you use BCM to resynchronize a Cnt Ac-S Z pair in an open/mainframe consistency group
with one primary and secondary system, all pairs in the consistency group are resynchronized.
Even if a Cnt Ac-S S-VOL is being accessed by a host, the pair is nevertheless resynchronized
with the others. Make sure to check the status of all pairs in the consistency group before
resynchronizing.
•
If you use BCM to delete a Cnt Ac-S Z pair in an open/mainframe consistency group with
one primary and secondary system, only the Cnt Ac-S Z pairs are deleted. Use RAID Manager
to delete the Cnt Ac-S pairs.
Requirements for a CTG for multiple primary and secondary systems
•
All requirements for a consistency group between one primary and one secondary system
apply to a consistency group between multiple primary and secondary systems.
•
The primary and secondary systems can be XP7 or P9500. No other models can be used.
•
A consistency group can consist of a maximum of four primary and four secondary (paired)
systems.
26 Planning for Continuous Access Synchronous