Hitachi ShadowImage for Mainframe User Guide: HP XP24000 Disk Array, HP XP20000 Disk Array (T5213-96032, May 2011)

Table 14 Additional Shared Memory for Differential Tables
Num. of Volumes in Storage
System
Num. of Pair TablesNum. of Differential TablesAdditional Shared Memory
for SIz
1,02400No additional shared
memory for SIz
16,3848,19226,176Additional shared memory
for SIz is installed
16,3848,19257,600Extension 1
65,53616,384104,768Extension 2
131,07216,384146,688Extension 3
1
131,07216,384209,600Extension 4
1
1 This can be used only in the XP24000 disk array.
To install additional shared memory for differential tables call the HP technical support.
Even if you install additional shared memory for differential tables and pair tables, the maximum
number of pairs is half of the total number of volumes in the storage system (see Table 14 (page
44)). For example, if additional shared memory for SIz is installed (second line in Table 14 (page
44)), and when S-VOLs and T-VOLs are in a one-to-one relationship, you can create up to 8,192
pairs. However, note that 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 SIz pairs, first you need to calculate how many differential
tables and pair tables are required to create SIz pairs, and then compare the result with the number
of differential tables and pair tables in the whole storage system. Note that in addition to
ShadowImage for Mainframe, the following program products will also use differential tables and
pair tables.
• Program products using differential tables
XP Business Copy◦
◦ FlashCopy Mirroring
◦ FlashCopy Mirroring V2
◦ XP Auto LUN
◦ XP Snapshot
• Program products using pair tables
ShadowImage for Mainframe◦
◦ FlashCopy Mirroring
◦ XP Auto LUN
If you use ShadowImage for Mainframe in the same storage system together with any or all of the
above program products, calculate the number of available differential tables and pair tables for
SIz pairs as follows:
(differential tables and pair tables in the whole storage system) – (the number of
differential tables and pair tables used by the pairs (migration plans in case of XP
Auto LUN) of the program products shown above) = (the number of available
differential tables and pair tables for SIz pairs).
For information about how to calculate the number of differential tables and pair tables that are
required for XP Business Copy, see the HP StorageWorks XP24000/XP20000 Business Copy
Software User's Guide, and as for FlashCopy Mirroring and FlashCopy Mirroring V2, see the HP
StorageWorks XP24000/XP20000 for FlashCopy Mirroring Software User's Guide. For information
44 Preparing for ShadowImage for Mainframe Operations