HP XP Business Copy Software - Manual (Page 34)

34 Business Copy XP (BC) for the XP10000/XP12000
to the root volume regardless of the status of L1/L2 pairs. Table 13 shows the relationship between
read/write operations from host to node volume and status of L1/L2 pairs. Table 14 shows the relationship
between read/write operations from host to leaf volume and L2 pair status.
Table 14 indicates the relationship between the read/write operation from the host to the leaf volume and
the L2 pair status.
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
was stopped before the split. With the At-Time Split function, LUN pairs are split at the same time within 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
executed.
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.
• A number (0–127) is assigned to each consistency group. You can specify a consistency group number
when you create BC pairs. If you do not specify a number, the disk array assigns a number
automatically.
• You can define up to 1,024 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
XP10000/XP12000.
• 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 ” on page 51).
Table 13 Read/write operation (host to the node volume) and L1/L2 pair status
L1 Pair
Status
L2 Pair Status
COPY(PD)
PAIR COPY(SP) PSUS(SP)/
PSUS
COPY(RS) PSUE
COPY(PD) Read Only Read Only Read Only Read Only Read Only Read Only
PAIR Read Only Read Only Read Only Read Only Read Only Read Only
COPY(SP) Read Only Read Only Read Only Read Only Read Only Read Only
PSUS(SP)/
PSUS
Read/
Write
Read/
Write
Read/
Write
Read/
Write
Read/
Write
Read/
Write
COPY(RS) Read Only Read Only Read Only Read Only Read Only Read Only
COPY(RS-R) Read Only Read Only Read Only Read Only Read Only Read Only
PSUE Read Only Read Only Read Only Read Only Read Only Read Only
Table 14 Read/write operation (host to the leaf volume) and L2 pair status
COPY L2 Pair Status
PAIR
COPY(SP) PSUS(SP)/PSUS COPY(RS) PSUE
Read Only Read Only Read Only Read/Write Read Only Read Only