Mailboxes are in Maildir format. Any good backup tips? Had success with version control?

[Thomas Harold]

On 6/30/2014 6:28 PM, deoren wrote:
> I'm still pretty new to running a mail server, but one thing I've come
> to appreciate over the years is a good backup strategy. Since I have
> always run my own servers for practice and for personal use I don't have
> access to Enterprise backup solutions. Because of that I usually just
> fall back to scripts and tarballs and offload the content on a regular
> basis.
> 

LVM snapshots of the file system combined with rdiff-backup to a second
server.

The main advantages over tar/rsync:

- Deltas instead of entire file. Plus deltas are compressed.

- It handles lots and lots of files well.

- You can easily age off older deltas.  Not hard to keep 26W or 52W of
daily or a few-times-per-day backups.

- Metadata such as file permissions / owner / group are stored in
regular files in the rdiff-backup target directory, so the destination
file system where you store the rdiff-backup files does not matter much.

- Files are stored along with a SHA1 hash, making it possible to detect
bitrot in your backups.

Downsides:

- Restoring a file more then 10 or 20 deltas old requires a lot of disk
activity (putting /tmp on a SSD helps a lot)

Suggestions:

- Each mailbox folder should be its own rdiff-backup target.  That
allows you to only backup mailbox folders which have changed in last N
hours/days.  It also means that if things go pear-shaped with
rdiff-backup, only that one backup target is at risk.

- Put /tmp on a SSD, especially if you run rdiff-backup "verify" and
validate more then 1-2 revisions into the past.

- Once you have your rdiff-backup directories on another server it is
trivial to LVM snapshot that and then rsync to either a USB drive or
offsite server (or both).  The rdiff-backup directory structure is very
rsync-friendly.

- If you're going to do hourly backups, have (2) rdiff-backup locations.
 One that deals with the hourly backups and has a short retention cycle
of only 3-4 weeks.  Another location that deals with daily backups and
has a 55W retention cycle.  That way you can restore to an hour within
the past 3-4 weeks, or any day within the past 55W.