It's almost required to lock down your JIRA instance when performing a full XML backup, so that the data isn't in an inconsistent (unrestorable) state. It's also recommended to use native database backups for disaster recovery. But, I don't see any recommendation about locking down your JIRA instance during native backups.
I don't know exactly how my native tool works, but what should I do to ensure a restorable native database backup?