[Dovecot] Director NFS backups

Hi All,

What is the recommended method of taking backups of user mailboxes when using the Director setup with NFS backend mail storage?    Is there any way to avoid the likely NFS locking issues by backing up the filesystem directly or do I have to do some sort of dsync method.  If I have to use dsync can I dsync the mailboxes to compressed copies of the mailboxes without requiring another dovecot server to do the dsync.  

Thanks for you responses.

Murray