Anon - 2019-03-20

I have several veracrypt files, and I would like to better understand when a backup of those files is or is not valid on macOS.

For example: Assume I have a 1GB file called 'foo' that is a veracrypt encrypted volume. I mount that volume as 'bar' -- which is never backed up by TimeMachine.

When 'foo' is mounted, if there is no open files in 'bar' when 'foo' is backed up, is the backup of 'foo' a valid backup? Is the backup of 'foo' valid if there are open files?

To generalize my question: When would a backup of 'foo' be valid and when would it not? I'm trying to understand what are my risks here, and when I have to unmount my VC volumes to ensure I have good backups of them.

Thanks!