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Table 12 Read/write operation (host to the leaf volume) and L2 pair status
L2 Pair Status
COPY
PAIR
COPY(SP)
PSUS(SP)/
PSUS
COPY(RS) PSUE
Read Only Read Only Read Only
Read/Write
Read Only Read Only
At-Time Split function
In the past, a BC pair group split each LUN pair in the group at a slightly different time. If the application
data spanned multiple LUNs in the group, there was the chance of data corruption unless the application
wasstoppedbeforethesplit.WiththeAt-TimeSplitfunction,LUNpairsaresplitatthesametimewithin
the group, which keeps data consistent without having to stop the application.
At this time, the At-Time Split operation is performed using RAID Manager on the UNIX/PC server host.
You can use Command View XP or XP Remote Web Console to perform BC pair operations for At-Time
Split pairs
created by RAID Manager. However, the At-Time Split option in Command View XP or
XP Remote Web Console is disabled.
A BC consistency group (CTG) is a user-defined set of BC volume pairs used for the At-Time Split
function. This function creates S-VOLs of all P-VOLs in the same consistency group when the pairsplit
command is e
xecuted.
BC consistency groups and the At-Time Split function have the following restrictions:
• You can configure up to 128 consistency groups in a disk array, including BC consistency groups.
• Anumber(0
–127) is assigned to each consistency group. You can specify a consistency group
number whe
n you create BC pairs. If you do not specify a number, the disk array assigns a
number automatically.
• You can define up to 4,096 BC pairs in a consistency group. However, for LUSE volumes
containing n LDEVs, you should count as n volumes. For more information about LUSE volumes,
see the HP StorageWorks LUN Configuration and Security Manager XP user guide for the
XP12000/XP10000.
• BC pairs
and ShadowImage pairs cannot co-exist in the same consistency group.
• To configure BC consistency groups, use the RAID Manager software. However, to confirm the BC
consistency group numbers, use BC (see Volume list).
When the At-Time Split function is enabled, data in all P-VOLs in the same consistency group is copied to
the corresponding S-VOLs when the disk array receives the pairsplit request from the host server. The
following figure shows an overview of the At-Time Split function.
36
Business Copy XP (BC) for the Array