[Dovecot] IMAP-proxy or not with sogo webmail and dovecot backend

[Timo Sirainen]

On 13.2.2012, at 21.36, Jan-Frode Myklebust wrote:

>> Other things that would be interesting to try out (both from latency and disk IO usage point of view):
>> 
>> - maildir_very_dirty_syncs
> 
> We already have
> 
> 	$ doveconf maildir_very_dirty_syncs
> 	maildir_very_dirty_syncs = yes
> 
> but I don't think this gave the advantage I was expecting.. Was
> expecting this to move most iops to the index-luns, but the maildir
> luns seems just as busy.

This setting should get rid of almost all readdir() calls. If it doesn't, something's not working right.

>> - mail_prefetch_count (Linux+maildir only, v2.1+)
> 
> Will look into if this works with GPFS when we upgrade to v2.1. It has
> it's own page cache, so I have no idea if it will respect
> POSIX_FADV_WILLNEED or if one will need to use it's own API's for
> hinting:
> 
> 	http://publib.boulder.ibm.com/infocenter/clresctr/vxrx/index.jsp?topic=%2Fcom.ibm.cluster.gpfs.v3r4.gpfs300.doc%2Fbl1adm_mlacrge.html

I guess if there's an easy way to lookup filename or fd -> blockNumber that wouldn't be difficult to implement with a plugin.