HP XP Business Copy Software - Manual (Page 44)

in Table 14 (page 43) ), and when P-VOLs and S-VOLs are in a one-to-one relationship, you
can create up to 8,192 pairs. However, in the case of Extension 2 to Extension 4, the maximum
number of pairs is 16,384, regardless of the total number of volumes in the storage system.
To calculate the maximum number of XP Business Copy pairs, you need to calculate how many
differential tables and pair tables are required to create XP Business Copy pairs, and then compare
the result with the number of differential tables and pair tables in the entire storage system. In
addition to XP Business Copy, the following program products will also use differential tables and
pair tables.
•
Program products using differential tables
ShadowImage for Mainframe ◦
◦ FlashCopy Mirroring
◦ FlashCopy Mirroring V2
◦ XP Auto LUN
◦ XP Snapshot
•
Program products using pair tables
ShadowImage for Mainframe ◦
◦ FlashCopy Mirroring
◦ XP Auto LUN
If XP Business Copy and these program products are used in the same storage system, the number
of available differential and pair tables for XP Business Copy pairs will be the total number of
available tables in the storage system minus the tables used by the above program products.
For information about how to calculate the number of differential tables and pair tables that are
required for ShadowImage for Mainframe, see the XP Business Copy™ for Mainframe User Guide:
HP XP24000 Disk Array, HP XP20000 Disk Array. For FlashCopy Mirroring and FlashCopy
Mirroring V2, see the HP StorageWorks XP24000/XP20000 for FlashCopy Mirroring Software
User Guide. Also, see the HP StorageWorks XP24000/XP20000 Auto LUN Software User Guide
to calculate the number of differential tables and pair tables that are required for XP Auto LUN.
See the HP StorageWorks XP24000/XP20000 Snapshot User Guide to calculate the number of
differential tables and pair tables that are required for XP Snapshot.
Assuming that only XP Business Copy uses differential tables and pair tables, this section describes
how to calculate the number of differential tables and pair tables required for one XP Business
Copy pair, and the conditions you need to consider when calculating the number of XP Business
Copy pairs that can be created.
You can use RAID Manager’s inqraid command to query the number of the differential tables and
pair tables required when you create XP Business Copy pairs. You can also query the number of
the differential tables and pair tables not used in the storage system by using this command. For
details about inqraid command, see the HP StorageWorks XP RAID Manager User Guide.
Calculation of the Number of Differential Tables and Pair Tables Required for One Pair
When you create an XP Business Copy pair, the number of required differential tables and pair
tables will change according to the emulation type of the volumes. To calculate the number of
differential tables and pair tables required for a pair according to the emulation type, use the
expression shown in
Table 15 (page 45) .
44 Preparing for XP Business Copy Operations