HP StorageWorks XP Remote Web Console Software - Manual (Page 83)

The XP Snapshot function is enabled automatically by specifying the consistency group number.
2. Execute the paircreate command again by specifying the same consistency group number
specified in step 1.
You can add pairs into the same consistency group. Repeat this step for each number of pairs
that you want to specify into the same consistency group.
3. Execute the pairsplit command to the consistency group that is a target of the At-Time
Snapshot function.
After the XP24000/XP20000 Disk Array accepts the pairsplit command, the snapshot
data of the P-VOL will be stored at the time when the host issues an I/O request to each P-VOL
in the corresponding consistency group.
Consistency group:
•
You cannot specify the XP Snapshot pairs in the same consistency group if the pairs share
the same volume as P-VOL. If you specify these pairs in the same consistency group, the
paircreate
command will be rejected.
•
You should not mix pairs created with the At-Time Snapshot option and without the At-Time
Snapshot option in the same group as the group which is defined in the RAID Manager
configuration file. This group differs from the consistency group. If you mix these two
types of pairs, the pairsplit command may terminate abnormally. Additionally, it is
not recommended that the stored snapshot data is the P-VOL data at the time when the
XP 24000/20000 Disk Array accepts the pairsplit command.
•
You can specify only 1 consistency group for each group that is defined in the RAID
Manager configuration file.
When you create a pair by using the group that is defined in the RAID Manager
configuration file, if some pairs specifying consistency group has been created in the
group already, you should create a pair by specifying the same consistency group as
the corresponding pairs. Even if you try to create a pair by specifying the other consistency
group, the pair will be added to the same consistency group as the corresponding pairs.
If you want to specify plural consistency groups, define as many groups as the consistency
groups that you want to specify in the RAID Manager configuration file.
•
Cautions for storing snapshot data:
When the pairsplit command is issued, if the corresponding consistency group includes
the pairs that are not in the PAIR status, the pairsplit command processing may
terminate abnormally.
The causes of abnormal end are as follows:
◦ Command rejection
◦ Timeout (Error code: EX_EWSTOT)
◦ Suspending the pair (Error code: EX_EWSUSE)
While executing the pairsplit command, if the other operation (deletion of snapshot
data or deletion of XP Snapshot pairs, etc.) is executed to the pairs in the corresponding
consistency group, the consistency of the stored snapshot data cannot be ensured.
Therefore, the pairsplit command processing may terminate abnormally.
The causes of abnormal end are as follows:
◦ Command rejection
◦ Timeout (Error code: EX_EWSTOT)
◦ Suspending the pair (Error code: EX_EWSUSE)
Storing XP Snapshot Data by Consistency Group with At-Time Snapshot Function 83