HP StorageWorks XP Remote Web Console Software - Manual (Page 22)

Shared Memory Capacity for the Whole V-VOL Manage-
ment Area If a Shared Memory is Added to
1,610,612,736 bytes Extension 2
2,147,483,648 bytes Extension 3
To calculate the maximum number of XP Snapshot pairs you can create for an array, use the following
formula:
Maximum number of XP Snapshot pairs = Total capacity of P-VOLs / { (Capacity of one P-VOL /
4194304) x4194304}
4194304: Unit by which pool association information manage the capacity of a P-VOL (in Kilobytes).
NOTE:
You must round up the value enclosed by two upward arrows ( ) to the nearest whole number.
NOTE:
Pool association information manages the P-VOL capacity by 4 GB. For example, if the capacity of
a P-VOL is 10 GB, pool association information capacity will be 12 GB, not 10 GB.
To calculate the total capacity of P-VOLs, use the formula below:
Total capacity of P-VOLs = (S1 / 74784) x 16384 x 256
S1 — Shared memory capacity for pool association information (in bytes) 74784: Capacity of pool
association information per one table (in bytes) 16384: Number of slots of P-VOL which can be
managed by the pool association information of one table 256: Capacity of one slot (in kilobytes).
NOTE:
You must round up the value enclosed by two upward arrows ( ) to the nearest whole number.
To calculate S1 (Shared memory capacity for pool association information), use the formula below:
S1 = S – S2 - 8388608
S — Shared memory capacity for the whole V-VOL management area (in bytes)
S2 — Shared memory capacity for pool management block (in bytes)
8388608: Fixed management information (in bytes).
Requirements for XP Snapshot operations 22