HP XP Business Copy Software User Manual
Page 47
Conditions for the Number of XP Business Copy Pairs That Can Be Created (When LUSE Volume
Exists)
The number of XP 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 XP Business Copy
pairs that can be created when LUSE volumes are used.
When you use LUSE volumes, you can use the following equation to know whether you will be
able to create the desired number of XP Business Copy pairs or not.
You need to satisfy the inequalities below.
[ {( ) x (the number of the volumes that forms LUSE volumes)} x (the number of
XP Business Copy pairs)]
( )
and also
[ {( {( x (the number of the volumes that forms LUSE volumes)} x (the number of
XP Business Copy pairs)]
( )
•
( ): The required number of differential tables for each volume that forms LUSE volume.
When you use LUSE volumes to create an XP Business Copy pair, every volume that forms the
LUSE volume will use the differential tables as a pair. For example, if you create an XP 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.
( ) changes according to the emulation type. For information about how to calculate ( ), see
.
•
( ): The number of differential tables available in the storage system.
( ) differs according to the installed additional shared memory for differential tables. For
details, see
“Additional Shared Memory for Differential Tables” (page 43)
.
•
( ): The required number of pair tables for each volume that forms LUSE volume.
( ) changes according to the value of ( ). For information about how to calculate ( ), see
.
•
( ) : The number of pair tables available in the storage system.
( ) differs according to the installed additional shared memory. For details, see
Shared Memory for Differential Tables” (page 43)
.
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 equation:
(3 x 3) x 10 = 90
26,176
and also
(1 x 3) x 10 = 30
8,192
Therefore, you can see that 10 XP Business Copy pairs, that are formed by three OPEN-3, volumes
can be created.
Assessing Requirements
47