HP XP Business Copy Software - Manual (Page 25)

• Normal. This operation (see Figure 4 ) resynchronizes the S-VOL with the P-VOL. The copy direction
for a normal pairresync operation is P-VOL to S-VOL. The pair status during a normal resync oper-
ation is COPY(RS), and the P-VOL remains accessible to all hosts for read and write operations
during a normal pairresync.
• Quick. This operation speeds up the normal pairresync operation without copying the P-VOL data
to the S-VOL. The P-VOL and S-VOL are resynchronized when update copy operations are performed
for duplex pairs (status = PAIR). The pair status during a quick pairresync operation is PSUS(SP)
until the differential map is copied, and the P-VOL remains accessible to all hosts for read and
write operations. The S-VOL becomes inaccessible to all hosts during a quick pairresync operation.
Figure 4 Normal and quick pairresync operations
.
CAUTION:
Even if a copy operation is completed without any host I/O, the data in the P-VOL and S-VOL may
not be identical. Whether the P-VOL and the S-VOL have the same data depends on the condition
of the disk array. To make the P-VOL and S-VOL data the same, split the pair and make the pair
status PSUS.
Backward pairresync operation
A backward pairresync operation resynchronizes pairs by copying data on S-VOLs to P-VOLs. The
following are the types of backward pairresync operations:
• Reverse. This operation (see Figure 5 ) synchronizes the P-VOL with the S-VOL. The copy direction
for a reverse pairresync operation is S-VOL to P-VOL. Table 6 shows the requirements for reverse
and quick restore pairresync operations. If you perform these operations on pairs that do not meet
XP Business Copy User Guide 25