HP XP Business Copy Software - Manual (Page 20)

Since 3,870 is less than 13,652, 10 pairs of OPEN-3 volumes and 20 pairs of OPEN-V volumes can
be created.
NOTE:
When the emulation type is OPEN-3, and the capacity of the volume is 2,403,360 KB, the number
of differential tables required for a pair is 1. When the emulation type is OPEN-V, and the capacity
of the volume is 3,019,898,880 KB, the number of differential tables required for a pair is193.
Calculating the number of BC pairs if LUSE is used
Use the following equation to calculate whether the desired number of BC pairs can be created:
[ {( ) x (number of volumes that form LUSE volumes)} x (number of BC pairs)] ( ), where:
• ( ) is the required number of differential tables for each volume that forms the LUSE volume.
When you use LUSE volumes to create a BC pair, every volume that forms the LUSE volume uses
the differential tables as a pair. For example, if you create a BC pair by using LUSE volumes that
are created by combining two OPEN-V volumes, you need differential tables for two OPEN-V
pairs.
• ( ) is number of differential tables in the disk array.
• ( ) = 13,652 when additional shared memory for differential tables is not installed.
• ( ) = 30,718 when additional shared memory for differential tables is installed.
For example, if you create 10 pairs of LUSE volumes consisting of three OPEN-3 volumes, use the
following equation:
(1 x 3) x 10 = 30 13,652
Since 30 is less than 13,652, 10 pairs of LUSE volumes consisting of three OPEN-3 volumes can be
created.
NOTE:
When the emulation type is OPEN-3, and the capacity of the volume is 2,403,360 KB, the number
of differential tables required for a pair is 1.
BC operations
Set reserve attribute operation
This operation reserves a volume so it can be used as a BC S-VOL. Reserved volumes can only be
used as BC S-VOLs. The disk array rejects all write operations to reserved volumes (unless in split
(PSUS) status or PSUS(SP)). You can reserve up to 4,095 volumes in one disk array. Use the Set
Reserve Attribute window (see
Setting reserve attributes ) to reserve volumes for use as BC S-VOLs.
A volume might be reserved for BC to ensure that a server does not mount it before BC can use it in
a pair. BC cannot use a volume as an S-VOL if it is being used by a server.
Business Copy XP (BC) for the Array 20