HP XP RAID Manager Software - Manual (Page 16)

NOTE: You can check the capacity of the shared memory of pool association and pool
management block information in Remote Web Console's Snapshot window.
For example:
S2 = ceil[{(4,282,451,296 ч 256) Ч 32} ч 8,736] Ч 8,736 + ceil[{(4,282,451,296 ч 256) ч 270} ч 2,048 ] Ч 8,736
= ceil[61,275.917...] × 8,736 + ceil[30.252...] Ч 8,736
= 61,276 Ч 8,736 + 31 Ч 8,736
= 535,577,952
3. Calculate shared memory capacity for pool association information (S1), using the following
formula:
S1 = S – S2
where:
S = Shared memory capacity for the whole V-VOL management area (in bytes)
S2 = Shared memory capacity for pool management block (in bytes)
For example:
This example assumes that S is 716 MB (751.619,276 bytes).
S1 = 751,619,276 – 535,577,952
= 216,041,324
4. Calculate the total capacity of P-VOLs, using the following formula:
Total capacity of P-VOLs = ceil(S1 ч 8,736) Ч 2,048 Ч 256
where:
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 P-VOL that can be managed by the pool association information of
one table
256 = capacity of one slot (in kilobytes)
For example:
Total capacity of P-VOLs (kB) = ceil[(216,041,324 ч 8,736)] Ч 2,048 Ч 256
= ceil[24,731.005...] Ч 2,048 Ч 256
= 24,731 Ч 2,048 Ч 256
= 12,966,166,528
5. Calculate maximum number of pairs, using the following formula:
Max. num. Snapshot pairs = Total capacity of P-VOLs (in kilobytes)
÷ {ceil[(Capacity of one P-VOL (in kilobytes) ч 524,288)] Ч 524,288}
where:
524,288 = unit by which pool association information manages the capacity of a P-VOL (in
kilobytes)
For example:
This example assumes that the capacity of one P-VOL is 10 GB.
Max. num. Snapshot pairs = 12,966,166,528 ÷
ceil[[{(10 Ч 1,024 Ч 1,024) ч 524,288}] Ч 524,288]
= 12,966,166,528 ч 10,485,760
= 1,236
All examples in order:
P = 4,294,967,296 – (4,116,000 + 84,000 × 100)
= 4,282,451,296
S2 = ceil[{(4,282,451,296 ч 256) Ч 32} ч 8,736] Ч 8,736 +
ceil[{(4,282,451,296 ч 256) ч 270} ч 2,048 ] Ч 8,736
= ceil[61,275.917...] × 8,736 + ceil[30.252...] Ч 8,736
= 61,276 Ч 8,736 + 31 Ч 8,736
16 Planning and design