HP StorageWorks XP Snapshot Software user guide: HP XP12000, HP XP10000, HP 200 Storage Virtualization System (T1713-96026, March 2009)
Example
S2=
[{4398046511104 / (256 x 1024)} x (32 / 74784)] x 74784
=
7178.9542... x 74784
= 536874336
S1= 1073741824 536874336 8388608
= 528478880
Total capacity of P-VOLs (kB) =
(528478880 / 74784) x 16384 x 256
=
7066.737... x 16384 x 256
= 7067 x 16384 x 256
= 29641146368
Maximum number of XP Snapshot pairs will be as follows:
Maximum number of XP Snapshot pairs = 29641146368 / [
{(10 x 1024 x 1024) / 4194304} x4194304]
= 29641146368 / 12582912
= 2355.666...
= 2355
According to these results, you can create a maximum of ,2,355 XP Snapshot pairs.
If a shared memory is added to your storage subsystem and you know the pool capacity, you can
estimate the capacity of a P-VOL that can be created, as explained in Table 6 on page 24. To calculate
the actual capacity of a P-VOL that can be created, use the above formulas.
Table 6 Estimate of Capacity to Create a P-VOL
And If the Pool Capacity isIf a Shared Memory is Added to
10,240
GB
8,192
GB
6,144
GB
4,096
GB
2,048
GB
1,024
GB
nananana10 TB15 TBBasicXP12000 Disk Array
nana10 TB21 TB32 TB37 TB
Exten-
sion 1
10 TB21 TB32 TB43 TB54 TB59 TB
Exten-
sion 2
32 TB43 TB54 TB65 TB76 TB81 TB
Exten-
sion 3
nananana3 TB10 TBXP10000 Disk Array
Using the number of pair tables
Hitachi FlashCopy Mirroring Version 2 and XP Snapshot pairs use pair tables to store control
information needed to manage pairs. To create an Hitachi FlashCopy Mirroring Version 2 or XP
Snapshot pair, you need one pair table for each pair.
Usually, up to 32,768 pair tables are available in one array. However, if the relationship expansion
function, which is an Hitachi FlashCopy Mirroring Version 2 function, is enabled, the maximum number
of available pair tables in one array is 1,048,575.
Among array software products, only Hitachi FlashCopy Mirroring Version 2 and XP Snapshot use
pair tables. Therefore, if you use Hitachi FlashCopy Mirroring Version 2, calculate the number of
Requirements for XP Snapshot operations24