You can back up a single Writable Volume or multiple volumes from the App Volumes Manager.
If you choose to back up the volumes in the background, and they are still attached at the time of the back up, the back up will occur after the volumes get detached.
Note: Multiple volumes can only be backed up as a background job.
When you perform a Writable Volume backup operation, any previous backup of the Writable Volume is purged and then a new backup is created.
You can also schedule regular backups in App Volumes Manager. See Set Up Regular Writable Volumes Backups.