HP StorageWorks XP Remote Web Console Software - Manual (Page 87)

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)
The restoration of the XP Snapshot pair sometimes ends abnormally for any of the following
reasons:
◦ The snapshot data of the XP Snapshot pair for restoration is being stored per
consistency group.
◦ The P-VOL of the XP Snapshot pair for restoration is used as the P-VOL of another XP
Snapshot pair, and the snapshot data of the latter XP Snapshot pair is being stored
per consistency group.
•
Caution for when the host server is down or has failed:
When the host server is down or has failed, a consistency group without any XP Snapshot
pairs may be created. If you create pairs that are the target of the At-Time Split option
from XP RAID Manager under such a condition, the command might be rejected. In this
Storing XP Snapshot Data by Consistency Group with At-Time Snapshot Function 87