On 9/25/2012 12:29 AM, Spyros Tsiolis wrote:
My clients don't invest in hardware. I live in Greece. Things are really bad right now. Not that if they were better they (the client) would invest in their infrastructure. ... Thank you very much Stan for you kind reply.
I reply to you in private since I was told to stop the thread on the dovecot list because it's off-topic.
I'm going to bring it back on topic. To recap the issue:
- 73GB volume, ~82% full. Volume contains OS, spool, and mailboxes
- Two 146GB drives on hand that are impossible to employ in either a live or offline migration due to hardware limitations--drive slots
(0.82*73GB=60GB)-5GB(OS)= ~55GB/40= ~1.375GB/user mailbox
(This math assumes the box has already been scoured and things like source files and other temporary stuff has already been removed, along with anything and everything not necessary to the primary functions of this box)
1.375GB/user suggests these users seem to horde old emails, or simply don't keep their mailboxes tidy. Normally I'd guess that a lot of space in a situation like this is taken up by full text search indexes, but you don't appear to have these enabled.
I notice in your 'dovecot -n' output that you are already employing zlib, but to what degree is currently unknown to the list. Are you compressing maildirs with a nightly script? If not, and you're compressing on an ad hoc basis, realtime compression during write could save you quite a bit of additional space, extending the operating life of your current drives. Of course a simple request to your users to clean up their mailboxes would surely help as well, if that's a possibility--some users would flog one for making such a suggestion.
If you're not fully taking advantage of compression currently, you may want to consider upgrading to Dovecot 2.x which allows transparent compression to dbox and maildir storage. You may want to migrate to mdbox message store format while still using zlib, and enable single instance attachment storage (SIS). As the name suggests, SIS saves an attachment only once, regardless how many user emails in which it exists. See:
http://wiki2.dovecot.org/Plugins/Zlib
I'd point you to the docs for SIS but I'm unable to find them in the Wiki. Surely someone else can provide the settings and/or update the wiki.
-- Stan