HP StorageWorks XP Remote Web Console Software - Manual (Page 29)

Table 16 Additional Shared Memory for the V-VOL Management Area
Shared Memory Shared Memory Capacity
XP Snapshot 1 751,619,276 bytes
XP Snapshot 2 1,073,741,823 bytes
XP Snapshot 3 2,147,483,647 bytes
To calculate the maximum number of XP Snapshot pairs that can be created for a subsystem, use the
formula below:
Maximum number of XP Snapshot pairs = Total capacity of P-VOLs ÷
{↑(Capacity of one P-VOL ч 512)↑ Ч 512}
512: Unit by which pool association information manages the capacity of a P-VOL (in megabytes)
Note that you must round up the value enclosed by the two upward arrows (↑) to the nearest whole
number.
Note: Pool association information manages the P-VOL capacity by 512 GB.
To calculate the total capacity of P-VOLs, use the formula below:
Total capacity of P-VOLs = ↑(S1 ч 8,736)↑ Ч 2,048 Ч 256
S1: Shared memory capacity for pool association information (in bytes)
8,736: Capacity of pool association information per one table (in bytes)
2,048: Number of slots of the P-VOL which can be managed by the pool association information for one
table
256: Capacity of one slot (in kilobytes)
Note that you must round up the value enclosed by the 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 - 10
S: Shared memory capacity for the whole V-VOL management area (in bytes)
S2: Shared memory capacity for the pool management block (in bytes)
10: Fixed management information (in megabytes)
Note: You can check the capacity of the shared memory of the pool association information and the pool
management block in the XP Snapshot window. See Figure 8 on page 42.
To calculate S2 (shared memory capacity for pool management block), use the formula below:
S2 = ↑[{{P ч 256) Ч 32} ч 8,736]↑ Ч 8,736 + ↑[{{Y ч 256} ч 272} ч
2,048]↑ Ч 8,736
P: Total capacity of all pools (in kilobytes)
Y: Total capacity of the pool-VOLs (in kilobytes)
256: Capacity of one slot (in kilobytes)
32: Capacity of the table which you need to manage the pool of one slot
8,736: Minimum size of the pool management block (in bytes)
272: Number of slots that can be managed by the slot management table
2,048: Number of slots that can be managed by the pool management block of the minimum size
XP24000 Snapshot User's Guide 29