[Dovecot] Performance-Tuning

[Jan-Frode Myklebust]

On Wed, Nov 16, 2011 at 11:53:29PM -0200, Henrique Santos Fernandes wrote:
> 
> Wich clustered filesytem do you have?

We use IBM GPFS, with currently 7 servers working against shared LUNs
from an IBM DS4800.

> 
> My ocfs2 setup had some problems... but still..
> Some numbers:
> 
> OCFS2
> 1TB of maildir files.
> Full backup 36 Hours
> Incremental 15 hours
> 
> Ext4
> 1TB of maildir files.
> Full backup 16 Hours
> Incremental 1 hour

Wow, local fs's are fast!

We have split the backup process up to run on 6 of the servers, with each
server processing only a part of the filesystem (/a-f, /g-l, /m-p, etc..).
The backup processing time varies quite a bit every day, but are mostly
somewhere between 14-24 hours on each server. This sounds like something
between 1.5x to 2x the incremental-performance you're seeing:

	15 hours/incremental of 1TB ocfs2 = 15h/TB
	6x 15 hours for incremental of 12 TB GPFS = 7.5h/TB 
	6x 20 hours for incremental of 12 TB GPFS = 10h/TB 

All our backups are incremental.


  -jf