Hp StorageWorks XP Remote Web Console Software Manual de usuario descargar pdf (Pagina 28)

Calculating the

Number of XP Snapshot Pairs by Using the Number of Differential Tables

If additional sh

ared memory is installed, the maximum number of differential tables will be 26,176 or

57,600 or 104,768 or 146,688 or 209,600. To calculate the number of XP Snapshot pairs that can be

created, calculate the number of differential tables required for the XP Snapshot pair and compare it with

the number of di

fferential tables of the whole subsystem. Other than XP Snapshot, the following program

products use di

fferential tables in the storage system:

• Business Copy

• ShadowImage for Mainframe

• Compatible Fl

ashCopy Version 1

• Compatible FlashCopy Version 2

• Auto LUN

If any of the a

bove mentioned program products other than XP Snapshot are used in the same subsystem,

the number of

differential tables that can be used by XP Snapshot pairs is calculated by subtracting the

number of di

fferential tables used by the pairs (migration plan for Auto LUN) of the above mentioned

program pro

ducts from the number of differential tables of the whole subsystem.

Please see t

he manual of each program product for the calculation of the number of required differential

tables for

Business Copy, ShadowImage for Mainframe, Compatible FlashCopy Version 1, Compatible

FlashCopy Version 2, and Auto LUN.

To calculate the number of differential tables for each XP Snapshot pair, use the formula below:

((X) ÷ 256) ÷ (Z)

(X): Capacity of the volume (in kilobytes)

(Z): The number of slots that a differential table can manage (1,916 × 32)

Note that you must round up the result of the calculation to the nearest whole number.

When the capacity of the volume ((X) in the formula above) is 16 GB (16,777,216 kB), the number of

differential tables for each XP Snapshot pair can be calculated as follows.

Exampl

(16,777,216 ÷ 256) ÷ (1,916 × 32) = 1.06889

1.06889 will be 2 when the value after the decimal point is rounded up. This indicates that two

differen

tial tables are required to create an XP Snapshot pair.

Assume that no other program products use differential tables in a subsystem where the number of

differential tables is 26,176. The number of differential tables that XP Snapshot can use is 26,176. To

create Snapshot pairs that require two differential tables for each pair, the calculation will be as follows.

26,176 ÷

2=13,088

Thus, the maximum number of XP Snapshot pairs that can be created is 13,088.

Calculating the Number of XP Snapshot Pairs by Using the Shared Memory Capacity for the

Virtual Volume Management Area

The V-VOL management area consists of the following three elements.

• Pool association information

• Pool management block

• Management information other than those above (shared memory is ﬁxed to 10 MB)

The shared memory of the V-VOL management area differs according to the additional shared memory.

The following table shows the detailed information.

Preparing for XP Snapshot Operations

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 81 82

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Hp StorageWorks XP Remote Web Console Software Manual de usuario Pagina 28

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