The XADDPAIR TSO command specifies both the primary (source) and
secondary (target) volumes of a volume pair that you want to add to
an XRC session. You can add up to 50 volume pairs with each XADDPAIR
command.
Note: - When you add a suspended volume pair back to the session, the
data on the recovery (target) volume is incomplete (not ready for
recovery) until the volume pair reaches duplex state. Choose the resynchronization
time carefully to allow the volume pairs to quickly reach duplex state.
- After XRC processes an XADDPAIR command, it delays the start of
volume initialization slightly to allow you time to issue additional
XADDPAIR commands.
- A high-activity level on the primary volume’s storage
control can delay the initial volume copy process. XRC does not start,
or continue with, an initial volume copy or resynchronization process
on a storage control that exceeds the update threshold (HaltThreshold
parmlib parameter). If the volume pair’s copy-completed percentage
is not changing as expected, look at the STA field of the XQUERY VOLUME
report. If the status is "pnd" or "cpy" the copying has halted. If
the status is "PND" or "CPY" the copying has not halted. When the
activity level declines, the volume copy continues.
- When adding a volume pair using the LOGPLUS
parameter with the XADDPAIR command, be aware that any volume previously
activated by System Logger will be suspended by XRC if System Logger
is not currently active. If XADDPAIR results in the suspension of
a specified volume, issue an XQUERY and check the volume status.
L+ indicates that the volume was activated by System Logger. L- indicates
no System Logger connection for that volume.
This situation may also occur when volume pairs are re-added into
a session using the SUSPENDED parameter of the XADDPAIR command if
one or more of the volume pairs was initially added with the LOGPLUS
parameter.
If you find that XRC has suspended a L+ volume due
to System Logger inactivity, you can use the ICKDSF REFORMAT command
to clear the L+ flag in the volume label. More information can be
found in Device Support Facilities (ICKDSF) User's Guide and Reference.
- When adding LOGPLUS volumes, you may want to minimize impact to write
response time. Refer to Adding a volume with the LOGPLUS option.
- If a volume pair has been removed from the session with XDELPAIR,
it cannot be re-added until residual updates for the volume have been
drained from the primary storage subsystem cache. This process can
take several seconds to several minutes to complete, depending on
the current XRC session delay.
For additional information about the XADDPAIR command and to review
the XADDPAIR command syntax, refer to XADDPAIR–Adding volume pairs or utility volumes .