HP XP Business Copy Software - Manual (Page 20)

20 ShadowImage for the XP1024/XP128/XP12000/XP10000/SVS 200
volumes in one XP1024/XP128/XP12000/XP10000/SVS 200. Use the Set Reserve Attribute window (see
” Setting the Reserve Attribute ” on page 55) to reserve volumes for use as T-VOLs.
The SI390 reset reserve attribute operation unreserves a volume so that it can be varied online and
accessed by hosts. After you reset the reserve attribute, the XP1024/XP128/XP12000/XP10000/SVS 200
will accept all subsequent read and write I/O operations to the volume. Use the Reset Reserve Attribute
window (see ” Resetting the Reserve Attribute ” on page 57) to unreserve volumes.
NOTE: When TSO or ICKDSF commands are used to establish SI390 pairs, the T-VOLs do not need to be
reserved. The CESTPAIR and PPRCOPY ESTPAIR commands require that potential T-VOLs be offline to the
host.
Add Pair Operation
The SI390 add pair operation establishes the new specified SI390 pair(s). The volume that will be the
S-VOL must be in the simplex state, and the volume that will be the T-VOL must be reserved (if assigned
automatically) and simplex before being added to an SI390 pair. Use the Add Pair Dialog window (see
” Adding ShadowImage Pairs ” on page 58) to add (start) new SI390 volume pairs.
NOTE: Use the CESTPAIR and PPRCOPY ESTPAIR commands to add (start) SI390 pairs. For more
information on PPRC commands, see ” Using PPRC Commands for ShadowImage ” on page 76.
Initial Copy Operation
During the initial copy process, when you create a volume pair, ShadowImage for z/OS copies data in an
S-VOL to a T-VOL. The SI390 initial copy operation takes place when you add a new SI390 pair. The initial
copy operation copies all data on the S-VOL to the associated T-VOL(s). The S-VOL remains available to all
hosts for read and write I/Os throughout the initial copy operation. Write operations performed on the
S-VOL during the initial copy operation will be duplicated at the T-VOL(s) by update copy operations after
the initial copy is complete. The status of a pair is simplex before the initial copy operation. The status of
each pair is pending while the initial copy operation is in progress. The pair status changes to duplex
when the initial copy operation is complete. After initial copy is complete, write operations performed on
the S-VOL during the initial copy operation are duplicated at the T-VOL by update copy operations.
CAUTION: Even if the copy operation is completed without any host I/O, the data in the S-VOL and the
data in the T-VOL may not be the same. Whether the S-VOL and the T-VOL have the same data depends on
the condition of the disk array. To make the S-VOL data and the T-VOL data equal, split the pair and check
that the pair status split.