HP StorageWorks XP Remote Web Console Software - Manual (Page 30)

Re-synchronize Pair Operations (Normal, Quick, Reverse, Quick Restore)
To change the status of the pairs from Split to Duplex, or from Suspend to Duplex, you must re-synchronize
the pairs. Siz allows you to perform four different types of resync operations according to the speed
and direction of the resynchronization:
• Normal Copy (see section Forward Pairresync Operation , page 30)
• Quick Resync (see section Forward Pairresync Operation , page 30)
• Reverse Copy (see section “ Backward Pairresync Operation ” on page 31)
The Re-synchronize Volume Pair dialog box (see section
“ Re-synchronizing Hitachi ShadowImage for z/OS Pairs ” on page 83) allows
you to re-synchronize split and suspended Siz pairs. When the resync operation starts, the pair status
changes to resync or resync-r. When the resync is complete, the pair status changes to duplex. The
storage system resumes Siz update copy operations after the pair status changes to duplex. The S-VOL
remains fully accessible during a normal/quick resync operation, but becomes inaccessible to all hosts
during a reverse copy or quick restore operation. This ensures that the data on the S-VOL is identical to
the data on the T-VOL when the reverse copy or quick restore operation completes.
NOTE:
Siz allows you to perform normal/quick resync operations on split and suspended pairs, but reverse copy
operations can only be performed on split pairs.
Forward Pairresync Operation
Forward pairresync operation resynchronizes the pairs by copying the data of S-VOLs to T-VOLs. There
are two kinds of the forward pairresync operation, the normal pairresync operation and quick pairresync
operation.
• Normal: The normal resync operation (see Figure 7 , page 31) resynchronizes the T-VOL with the
S-VOL. The copy direction for a normal resync operation is S-VOL to T-VOL. The pair status during
a normal resync operation is resync, and the S-VOL remains accessible to all hosts for both read
and write operations during a normal resync operation. The T-VOL becomes inaccessible to
all hosts during a normal resync operation.
• Quick: The quick resync pair operation (see Figure 7 , page 31) speeds up the normal resync pair
operation by not copying the S-VOL data to the T-VOL right away. Instead, the T-VOL is gradually
re-synchronized with the S-VOL as host updates are performed, when update copy is scheduled
(XP1024/XP128/XP12000/XP10000/SVS 200 internal), or when a user issues another split
pair command for the pair. The S-VOL remains accessible to all hosts for both read and write
operations during a quick resync pair (same as normal resync pair). The T-VOL becomes
inaccessible to all hosts during a quick resync pair operation (same as normal resync pair).
30 Overview of Hitachi ShadowImage for z/OS Operations