[Dovecot] dovecot evaluation on a 30 gb mailbox

[Eric Rostetter]

Quoting "Daniel L. Miller" <dmiller at amfes.com>:

> On 6/24/2010 4:23 AM, Timo Sirainen wrote:
>>> I'd recommend also installing and configuring imapproxy - it can  
>>> be beneficial with squirrelmail.
>>>
>> Do you have any about a real world numbers about installation with  
>> and without imapproxy?
>
> What, you want me to actually back up that statement with data?!   
> Who do you think I am?!  Never mind - don't answer that.

I don't have any numbers either, but...

> I know when I was playing web clients - particularly squirrelmail -  
> there was a definite perceived improvement - but I never measured it.

Webmail clients are basically stateless.  Over time, they have "cached"
some info for performance, but basically they are still stateless.  So
almost any time you click on a link dealing with an email (delete, purge,
next message, forward, etc) it has to open a _new_ connection to the imap
(or pop) server, which means a new login.

Simple proxies (like say perdition) don't help, as each connection will
still be a new login.

Some proxies (like imapproxy) however can keep a login session open, with
the proxy caching the authentication issue.  For each connection after
the first, it can do the authentication itself and use the existing login
connection to the pop/imap server, avoiding a login for each operation after
the first (until a timeout is reached).  By avoiding the constant login/logout
cycle, it will generally perform at least slightly better with the proxy
than without (no new connection overhead, no login and logout overhead, same
over head most everywhere else unless the proxy's authentication is slow).

That's why a connection/authentication caching proxy is generally
recommended for webmail setups.  It also keeps the log files from filling
up on the pop/imap server with the constant login/logout log lines.

This is also why you can get a speedup even if the proxy is on the same host
as the pop/imap server (assume sufficient memory and other resources).

> Daniel


-- 
Eric Rostetter
The Department of Physics
The University of Texas at Austin

Go Longhorns!