HP XP RAID Manager Software - Manual (Page 17)

= 535,577,952
S1 = 751,619,276 – 535,577,952
= 216,041,324
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
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
Using the these examples, the maximum number supported based on additional shared memory
in the V-VOL management area is 1,236 pairs.
Pool capacity for shared memory and capacity of P-VOL which can be created is shown in the
following table.
Table 4 Pool capacity for shared memory and capacity of P-VOL which can be created
Pool capacity (GB) Shared
memory
30,720 20,480 14,336 12,288 10,240 8,192 6,144 4,096 2,048
- - - - - - - 11 (TB) 26 (TB) Snapshot
12 88 (TB) 133 (TB) 148 (TB) 163 (TB) 179 (TB) 194 (TB) 209 (TB) 224 (TB) Snapshot
Extension
(TB)
Calculate maximum pairs based on pair tables
A pair table keeps track of a pair's status. One pair table is used for one pair.
A storage system contains 1,048,575 pair tables.
Pair tables are used by Snapshot and Compatible FlashCopy pairs. Therefore, you must deduct
the number of Compatible FlashCopy pairs on the system from the number of pair tables to find
out how many Snapshot pairs you may create.
Determining maximum pairs allowed on your system
Use the calculations in the preceding sections to determined the maximum number of Snapshot
pairs your system supports.
For example: The example calculations in the preceding sections produced the following results:
•
6,544 Snapshot pairs were supported based on differential tables
•
3,020 Snapshot pairs were supported based on shared memory of the V-VOL management
area
•
1,048,575 Snapshot pairs were supported based on pair tables
Using the lowest value, then 3,020 pairs is the maximum number allowed on the example system.
Planning for external volumes
External volumes are volumes on external systems. Multiple external storage systems may be
connected to a P9500 system.
External volumes can be used as pool-VOLs. However, keep in mind that the pool will be blocked.
For example, if an external volume used as a pool-VOL is blocked, the pool becomes blocked as
well.
Planning for external volumes 17