[Dovecot] Zlib plugin - when does it make sense?
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
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?
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@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:
- CPU is not a problem, even delivering more than 400 messages per minute (blade HS21 with 2xQuad E5430 from 2008)
- 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
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?
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!
Am 25.11.2013 14:12, schrieb Everton Foscarini:
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:
- CPU is not a problem, even delivering more than 400 messages per minute (blade HS21 with 2xQuad E5430 from 2008)
- 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.
But this is due to the conversion to mdbox and not the compression, isn't it?
- René
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
- 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).
- 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
On 2013-11-25 14:35, Jan-Frode Myklebust wrote:
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
- 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).
Interesting! What zlib compression level did you use? I figure even low levels would work rather well for plain text.
Now that I think about "plain text": I also have the fts_solr plugin enabled to speed up the occasional full-text search - does the indexing still work as before when the mail is compressed, i.e. is the reading of the mail centralized so that the individual plugins don't actually know or care? Or would I need to make sure I use 'zlib-aware' plugins?
-- Frerich Raabe - raabe@froglogic.com www.froglogic.com - Multi-Platform GUI Testing
On Mon, Nov 25, 2013 at 02:47:33PM +0100, Frerich Raabe wrote:
Interesting! What zlib compression level did you use? I figure even low levels would work rather well for plain text.
plugin {
zlib_save_level = 6 # 1..9
zlib_save = gz # or bz2
}Now that I think about "plain text": I also have the fts_solr plugin enabled to speed up the occasional full-text search - does the indexing still work as before when the mail is compressed, i.e. is the reading of the mail centralized so that the individual plugins don't actually know or care? Or would I need to make sure I use 'zlib-aware' plugins?
I don't have fts (yet).
-jf
participants (4)
-
Everton Foscarini
-
Frerich Raabe
-
Jan-Frode Myklebust
-
René Neumann