[Dovecot] backup mdbox best strategy

[Claus]

Hello,

i have to backup (tape library) a mailsystem with about 300.000 
Mailboxes on 2 backends. Summary of all mailboxes are 2 TByte.
The mailstore is mdbox.
Is it save to do a simple filesystem backup (full and incremental) with 
backupsoftware?
What is the prefered strategy to do a backup for desaster recovery 
(mailsystem crash) and restoring single usermailboxes?


Regards,
Claus