On my "business" mailserver (courier-imap) I have 43 users (some of them
as On-Line-Archive), together over 42.000 mailfolders and 17.000.000
messages stored and each month we get 1800 mailfolders and 150.000
messages more. The total volume is arround 180 GByte. (real not blocks)
Currently I run a daily plus weekly cronjob with a selfmade script which
check first the /cur/ directories and if it does not match a previously
created MD5 + directory listing it will backuped. Daily incremental and
weekly full.
The daily incremental backup take arround 5 hours and the weekly full
backup arround 8 hours.
OK, the BaSH script works very fast but there is a problem with it...
It take 100% CPU resources... and it is nearly impossibel to connect
via IMAP to the server since the connection times out... :-(