Hi, I run a small IMAP server for a dozen guys in the office, serving about 55GB of Maildir. I recently became aware of the Zlib plugin ( http://wiki2.dovecot.org/Plugins/Zlib ) and wondered 1. given that there is about zero CPU load on my IMAP server, is enabling the plugin a no-brainer or are there other things (except CPU load) to consider? 2. For enabling the plugin, I suppose you compress all the existing mail just once and then add 'zlib' to mail_plugins in order to have all future incoming mail saved? Any insight by people familiar with the plugin would be much appreciated - thanks! -- Frerich Raabe - raabe at froglogic.com www.froglogic.com - Multi-Platform GUI Testing
I have a relatively big installation here in the university, 1 mail server for 10.000 daily active accounts. I converted from maildir to mdbox + zlib in march, and these are my considerations: 1. CPU is not a problem, even delivering more than 400 messages per minute (blade HS21 with 2xQuad E5430 from 2008) 2. I used dsync to convert from maildir to mdbox, with dovecot 2.1 at the time. The biggest win is the file number reduction, from 27 million to 2 million. Em 25/11/2013 06:53, Frerich Raabe escreveu:> Hi, > > I run a small IMAP server for a dozen guys in the office, serving > about 55GB of Maildir. I recently became aware of the Zlib plugin ( > http://wiki2.dovecot.org/Plugins/Zlib ) and wondered > > 1. given that there is about zero CPU load on my IMAP server, is > enabling the plugin a no-brainer or are there other things (except CPU > load) to consider? > > 2. For enabling the plugin, I suppose you compress all the existing > mail just once and then add 'zlib' to mail_plugins in order to have > all future incoming mail saved? > > Any insight by people familiar with the plugin would be much > appreciated - thanks! >
Jan-Frode Myklebust
2013-Nov-25 13:35 UTC
[Dovecot] Zlib plugin - when does it make sense?
On Mon, Nov 25, 2013 at 09:53:14AM +0100, Frerich Raabe wrote:> > I run a small IMAP server for a dozen guys in the office, serving > about 55GB of Maildir. I recently became aware of the Zlib plugin ( > http://wiki2.dovecot.org/Plugins/Zlib ) and wondered > > 1. given that there is about zero CPU load on my IMAP server, is > enabling the plugin a no-brainer or are there other things (except > CPU load) to consider?Yes, it's a no-brainer. I can't remember how the cpuload was before we enabled zlib, but our cpus are running 80% idle (6 servers, mix of IBM x3550 and x346, serving 15TB mdbox, but was serving maildir with zlib a year ago).> > 2. For enabling the plugin, I suppose you compress all the existing > mail just once and then add 'zlib' to mail_plugins in order to have > all future incoming mail saved?You don't strictly need to compress existing mail. It should handle a mix of compressed and non-compressed messages in the same maildir. -jf