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

[Mark Moseley]

On Mon, Feb 13, 2012 at 5:54 AM, Jan-Frode Myklebust <janfrode at tanso.net> wrote:
> We've been collecting some stats to see what kind of benefits
> UP/SquirrelMail's IMAP Proxy in for our SOGo webmail users. Dovecot is
> running in High-performance mode http://wiki2.dovecot.org/LoginProcess
> with authentication caching http://wiki2.dovecot.org/Authentication/Caching
>
> During the weekend two servers (webmail3 and webmail4) has been running
> with local imapproxy and two servers without (webmail1 and webmail2). Each
> server has served about 1 million http requests, over 3 days.
>
> server          avg. response time      # requests
> ----------------------------------------------------
> webmail1.example.net   0.370411        1092386
> webmail2.example.net   0.374227        1045141
> webmail3.example.net   0.378097        1043919  imapproxy
> webmail4.example.net   0.378593        1028653  imapproxy
>
>
> ONLY requests that took more than 5 seconds to process:
>
> server          avg. response time      # requests
> ----------------------------------------------------
> webmail1.example.net   26.048          1125
> webmail2.example.net   26.2997         1080
> webmail3.example.net   28.5596         808      imapproxy
> webmail4.example.net   27.1004         964      imapproxy
>
> ONLY requests that took more than 10 seconds to process:
>
> server          avg. response time      # requests
> ----------------------------------------------------
> webmail1.example.net   49.1407         516
> webmail2.example.net   53.0139         459
> webmail3.example.net   59.7906         333      imapproxy
> webmail4.example.net   58.167          384      imapproxy
>
> The responstimes are not very fast, but they do seem to support
> the claim that an imapproxy isn't needed for dovecot.

Out of curiosity, are you running dovecot locally on those webmail
servers as well, or is it talking to remote dovecot servers? I ask
because I'm looking at moving our webmail from an on-box setup to a
remote pool to support director and was going to look into whether
running imapproxyd would help there. We don't bother with it in the
local setup, since dovecot is so fast, but remote (but still on a LAN)
might be different. Though imapproxyd seems to make (wait for it...)
squirrelmail unhappy (complains about IMAP errors, when sniffing shows
none), though I've not bothered to debug it yet.