HP StorageWorks XP Remote Web Console Software - Manual (Page 12)

Split Pair Operation
The ShadowImage for Mainframe split capability provides point-in-time backup of your data, and
also facilitates real data testing by making the SIz copies (T-VOLs) available for host access. The
SIz split operation copies whole S-VOL data or differential data at that time to the T-VOL to make
the T-VOL identical to the state of the S-VOL when the split command was issued. If there are many
host I/Os for the S-VOL, it may take time to synchronize the S-VOL and the T-VOL. When the split
operation is complete, the pair status changes to split. Note that the split operations cannot be
performed on the pair whose status is suspend, resync or resync-R.
While the pair is split, the XP storage system establishes a differential bitmap for the split S-VOL
and T-VOL and records all updates to both volumes. The S-VOL remains fully accessible during the
split operation. Whether you can access the T-VOL depends on what split type is specified. There
are two kinds of split types, Quick Split and Steady Split. In addition to the split types, there is
At-Time Split which allows you to split all the pairs in the CTG. You can perform Quick Split and
Steady Split in the Split Volume Pair dialog box. You also need the XP for Business Continuity
Manager Software™ to perform At-Time Split.
•
Split pair operation by Quick Split:
When the quick split operation starts, the pair status changes to V-split. You have full read/write
access to the split T-VOL (even though it is still reserved). The whole S-VOL data or differential
data at that time will be copied to the T-VOL in the background.
For information about Read/Write operations from host servers to S-VOLs and T-VOLs of SIz
pairs during quick split operation, see
(page 73) .
•
Split pair operation by Steady Split:
When the steady split operation starts, the pair status changes to SP-pending. The whole S-VOL
data or differential data at that time will be copied to the T-VOL. When the steady split
operation is complete, you have full read/write access to the split T-VOL (even though it is still
reserved). To quickly finish the copy operation to access the T-VOL, make the S-VOL offline
before the operation.
For information about Read/Write operations from host servers to S-VOLs and T-VOLs of SIz
pairs during steady split operation, see
(page 73) .
•
Split pair operation by At-Time Split
To split pair by the At-Time Split function, you need the XP for Business Continuity Manager
Software™. To perform the split operation by using the At-Time Split function, you must specify
a copy group or register the split time in the copy group. The split time indicates the time when
you want to store the S-VOL data to the T-VOL. For example, if you register the CTG of
ShadowImage for Mainframe as the copy group of the XP for Business Continuity Manager
Software™, the At-Time Split function enables you to copy data from the SIz S-VOLs in the
same CTG to T-VOLs simultaneously. The T-VOLs will contain the same data as the S-VOLs
when the Split operation is performed.
Figure 4 (page 13) and Figure 5 (page 13) show the outline of the At-Time Split function.
12 About ShadowImage for Mainframe Operations