I always quiesce the system see below
Prior to starting my unattended backup process I end the following subsystems:
QINTER, QSPL, QHTTPSVR, QSNADS, QSVCDRCTR, QSERVER and QUSRWRK.
I also end the Mail Server Framework via the ENDMSF command.
I’m now in a “quiesced state”…. Note, my backup process is still running in the QBATCH subsystem.