Automating backups to an encrypted drive

[Alan Cox]

> Simply to leave the backups alone.  The only 'threat' would be that
> inadvertently a user could mess with the files on the backup drive.
> The backups happens every night and when they're done the drive is
> presently automatically unmounted for the day.  Works fine with
> unencrypted drives. 

You want any backup drive physically removed and unconnected most of the
time or a PSU failure/nearby lightning strike will blow both the original
disk and backup disk to kingdom come at once.