HP StorageWorks XP Remote Web Console Software - Manual (Page 45)

3 x 10 + 577 x 20 = 11,570 ≤ 26,167
and also
1 x 10 + 17 x 20 = 350 ≤ 8,192
Therefore, you can see that 10 pairs of OPEN-3 volumes and 20 pairs of OPEN-L volumes can be created.
Conditions for the Number of Business Copy Pairs that can be Created (LUSE Volume Exists)
The number of Business Copy pairs that can be created will change according to whether LUSE volumes
are used or not. This section describes how to calculate the number of Business Copy pairs that can be
created when LUSE volumes are used.
When you use LUSE volumes, you can use the following inequation to know whether you will be able to
create the desired number of Business Copy pairs or not.
You need to satisfy the inequalities below.
Σ[Σ {(α) × (the number of the volumes that forms LUSE volumes)} × (the number of
Business Copy pairs)] ≤ (β)
and also
Σ[Σ {(γ) × (the number of the volumes that forms LUSE volumes)} × (the number of
Business Copy pairs)] ≤ (δ)
• (α): The required number of differential tables for each volume that forms LUSE volume.
When you use LUSE volumes to create a Business Copy pair, every volume that forms the LUSE
volume will use the differential tables as a pair. For example, if you create a Business Copy pair
by using LUSE volumes that are created by combining two OPEN-V volumes, you need differential
tables for two OPEN-V pairs.
(α) changes according to the emulation type. For information about how to calculate (α), see
Table 9 on page 43.
• (β): The number of differential tables available in the storage system.
(β) will differ according to the installed additional shared memory for differential tables. For
details, see Table 8 on page 42.
• (γ): The required number of pair tables for each volume that forms LUSE volume.
(γ) changes according to the value of (α). For information about how to calculate (γ), see
Table 9 on page 43.
• (δ) : The number of pair tables available in the storage system.
(δ) will differ according to the installed additional shared memory. For details, see
Table 8 on page 42.
For example, if you are to create 10 pairs of LUSE volumes consisting respectively of three OPEN-3 volumes
in a storage system that has 26,176 differential tables, you can use the condition in equation as follows:
When the emulation type is OPEN-3, and if the capacity of the volume is 2,403,360 kB, the number of
differential tables required for a pair will be 3, and the number of pair tables required for a pair will be 1.
If you apply this number to the above-mentioned inequation:
(3 Ч 3) Ч 10 = 90 ≤ 26,176
and also
(1 Ч 3) Ч 10 = 30 ≤ 8,192
Therefore, you can see that 10 Business Copy pairs that are formed by three OPEN-3 volumes can
be created.
Performance Considerations
• When you operate Business Copy:
Business Copy operations affect the I/O performance of the storage system because of the copy
operations to the S-VOLs. You should consider the relative importance of the storage system’s
I/O performance and the Business Copy operations when you decide the number or structures of
pairs and their copy pace.
XP24000 Business Copy Software User's Guide 45