To instruct SQDR Plus to stop checking for updates during host maintenance (e.g. nightly backups), configure the agent property sourceMaintenanceWindow.
Alternatively, for a Db2 for i source, you can issue the following IBM i commands as a privileged user account:
/* at start of maintenance window */
SNDMSG MSG(PAUSE) TOMSGQ(SQDR/CAQ) MSGTYPE(*INQ) RPYMSGQ(*LIBL/QSYSOPR)
/* at end of maintenance window */
SNDMSG MSG(RESTART) TOMSGQ(SQDR/CAQ) MSGTYPE(*INQ) RPYMSGQ(*LIBL/QSYSOPR)
Note that in some cases the CAQ message queue may not be present; this indicates that the agent is not running. If you are invoking these commands from a CL program, make sure that your program handles this condition.
However, the existence of the CAQ does not necessarily indicate that the agent is running; it may still be present if the agent was terminated uncleanly or lost connectivity with the host.