Hi.
For a low-level view of what's going on on the filesystem, if you are running the cyr_expire daemon your log will have lines like:
cyr_expire[1234]: Expunged 135451 out of 78011390 messages from 277114 mailboxes
where the number of messages is the number of files and mailboxes are folders on all your data partitions of that server..
This log event gives an overview of the amount of data you need to backup (small files take much more time than large ones) as well as a growth indicator of your mail data if you keep your logs. It also allows for planning an outbound migration from Cyrus to something else and you get an idea of the average message size too (an estimation considering cluster disk size, etc etc) [then you hit the limit of max 500 MB/day upload on the destination provider ;) ].
You can certainly get a snapshot of the same information from the server CLI or any other backup/whatever service, if you have access to its stats.
Paolo
