[Dovecot] Proxying Performance vs imapproxy

[Jose Celestino]

On Seg, 2009-09-28 at 15:55 +0100, Ed W wrote:
> You didn't get much answer to this - I'm probably not the best person to 
> answer, but
> 
> > Are there any performance benefits to using a proxying server, or is it just
> > for splitting mailstores?
> >   
> 
> I think this is the main reason for the proxying option.  It would 
> appear that others have measured the performance load of the proxy task 
> and found it near negligible?  Hence it seems possible to use a bunch of 
> backend servers and a few frontend servers to forward the user to the 
> correct backend server.  I believe each connection needs to be setup 
> each time though, so for sure some more advanced proxies with persistent 
> caching of connections may offer a performance improvement if your 
> servers are loaded due to the login part (but I guess measure this first 
> before assuming it's so?)

Proxy servers are usually set between the webmail and the imap server.

That's because webmails are a bitch regarding opening+closing
connections and so the proxy gets most of connection + auth + do
something + disconnect and keeps a limited pool of per user connections
to the imap servers that it re-uses. Proxies are usually installed on
the same servers that the webmail, with the webmail connecting to
127.0.0.1:someport.

-- Jose Celestino SAPO.pt::Systems http://www.sapo.pt
--------------------------------------------------------------------- *
Progress (n.): The process through which Usenet has evolved from smart
people in front of dumb terminals to dumb people in front of smart
terminals.
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