Use the CSUSPEND command to
suspend PPRC operations between a primary
and secondary volume pair. PPRC stops transferring data to the secondary
volume. The primary storage subsystem, however, records all cylinders
that change on the primary volume (except when you specify the PRIMARY
option, as described in
this topic).
You can direct the CSUSPEND command to either
the primary or secondary
volume of a PPRC volume pair as a result of the DEVN parameter.
Note: - The ESS storage subsystem does not accept the CSUSPEND
command
with the PRIMARY parameter and fails the command if you specify the
PRIMARY parameter.
- Avoid issuing a CDELPAIR command following
a CSUSPEND command,
as this sequence can cause unpredictable results.
PRIMARY is an optional parameter of the SUSPEND command.
The results
of using it versus not using it are described as follows:
- When you do not specify PRIMARY option —
- PPRC
suspends the pair. Applications continue to update the
primary volume. These updates are not copied to the secondary volume,
but the storage control records which cylinders are changed while
the pair is suspended. When you reestablish the pair, specify the
RESYNC parameter of the CESTPAIR command to direct PPRC to copy only
the changed cylinders to the secondary volume. PPRC then returns the
secondary volume to duplex state.
This is the default option, and
you can address this option to the primary or the secondary volume.
- When you specify the PRIMARY option —
- PPRC
suspends the pair and unit checks all write data I/O that
is directed to the device, except for ICKDSF media maintenance channel
programs. When ICKDSF media maintenance operations have completed,
you can reestablish the pair with the CESTPAIR command with the RESYNC
option. (See Controlling ICKDSF activity to PPRC volumes for a PPRC volume
repair procedure.)
Only use the PRIMARY option as part of an ICKDSF media maintenance
procedure. Ensure that the DEVN parameter specifies the primary volume.
Issue the CESTPAIR command with the RESYNC option
to resume PPRC
operations for the volume pair.