There are some very rare cases in which backup job will run "forever".
With that said, we advise setting up the following settings in JetBackup to minimize the impact of this issue as much as possible:
We suggest setting up your Notifications (under Settings > Notification) and set the "Notify me if job process runs more than" Job Monitor on your Backup Job so that if the Backup Job runs for more than X number of days you will be notified of the issue. It is recommended to set the number of days to be higher than your average time of your backup job run. If the average time of your backup job is less then 10 hours, then setting this to "1" is reasonable.
Next is to set up the Kill zombie process id's under the General Settings so that JetBackup will automatically kill the Backup Job process if it reaches the set number of days processing. Again, ensure that you set the number of days to be higher than your average time of your backup job run. This way the Backup Job process will not be killed if actively running.
Once the Incremental Backups begin and you get a better baseline of the length an incremental Backup runs, we suggest lowering both the Job Monitor and Kill zombie process id's settings accordingly.
There is a known issue with CloudLinux servers when using JetBackup's default rsync /usr/local/jetapps/usr/bin/rsync
that can cause the Backup Job Run's Forever issue.
As a workaround, it is recommended to use the native rsync. To do so, navigate to Settings -> Binary location settings and change the default path to rsync.
Additionally, we highly suggest utilizing the suggestions above to help minimize the impact of this issue.