NDMP level 1-9 backup failed
NDMP backup aborted frequently on incremental (level 1-9 backups) due to inactivity timeout. There is a group inactivity timeout setting in the Group Resource in NetWorker. The default value is 30 minutes.
NAS devices takes a very long time to first walk the filesystem and compare file headers to determine which files have changed since the last lower level backup. When this exceeds the group timeout, the backup will fail.
Change the group inactivity timeout setting to 0 (zero) which is infinite and then see how long it is really taking to finish the backup and adjust the group inactivity timeout accordingly.