[Dovecot] vsz_limit

David Warden warden at geneseo.edu
Wed Feb 8 18:20:31 EET 2012


On Feb 8, 2012, at 3:58 AM, Héctor Moreno Blanco wrote:

-snip-

> service imap-login {
>  executable = /usr/local/dovecot/libexec/dovecot/imap-login
>  inet_listener imap {
>    address = *
>    port = 143
>  }
>  inet_listener imaps {
>    address = *
>    port = 993
>  }
>  process_limit = 2048
>  process_min_avail = 20
>  user = vmail
> }
> service imap {
>  executable = /usr/local/dovecot/libexec/dovecot/imap
>  process_limit = 2048
> }

- snip, again -

> 
> The problem is at the moment of maximum load of the system. We can see many imap sessions but there are also many imap-login processes, which is weird. Has it something to do with any parameter of our configuration? We think is something with the vsz_limit parameter. How can we tune it?

I'm not 100% sure but if this is the case but it looks like you setting process_limit and process_min_avail in the imap-login service block is putting dovecot in "High Security" mode. http://wiki2.dovecot.org/LoginProcess has good details on that. In short, I suspect your settings are creating a new imap-login process for each new IMAP connection. As I understand it, vsz_limit is more important when running in "High Performance" mode where you have just 1 imap-login process that handles all new IMAP connections. That process can grow quite large if you have a lot of simultaneous IMAP clients.

> 
> Thank you very much in advanced.
> 
> Kind regards.
> 
> ________________________________
> [cid:image001.gif at 01CCE647.65B8FB30]
> 
> Héctor Moreno Blanco
> División de Seguridad e Infraestructuras /
> Security and Infrastructures Division
> 
> GMV
> Isaac Newton, 11
> P.T.M. Tres Cantos
> E-28760 Madrid
> Tel. +34 91 807 21 00
> Fax +34 91 807 21 99
> www.gmv.com <http://www.gmv.com/>
> [cid:image002.gif at 01CCE647.65B8FB30]<http://www.gmv.com/b2_gmv>
> 
> 
> 
> [cid:image003.gif at 01CCE647.65B8FB30]<http://www.facebook.com/infoGMV>
> 
> 
> 
> [cid:image004.gif at 01CCE647.65B8FB30]<http://www.twitter.com/infoGMV_es>
> 
> 
> 
> [cid:image005.gif at 01CCE647.65B8FB30]<http://www.youtube.com/infoGMV>
> 
> 
> 
> 
> 
> 
> ______________________
> This message including any attachments may contain confidential 
> information, according to our Information Security Management System,
> and intended solely for a specific individual to whom they are addressed.
> Any unauthorised copy, disclosure or distribution of this message
> is strictly forbidden. If you have received this transmission in error,
> please notify the sender immediately and delete it.
> 
> ______________________
> Este mensaje, y en su caso, cualquier fichero anexo al mismo,
> puede contener informacion clasificada por su emisor como confidencial
> en el marco de su Sistema de Gestion de Seguridad de la 
> Informacion siendo para uso exclusivo del destinatario, quedando 
> prohibida su divulgacion copia o distribucion a terceros sin la 
> autorizacion expresa del remitente. Si Vd. ha recibido este mensaje 
> erroneamente, se ruega lo notifique al remitente y proceda a su borrado. 
> Gracias por su colaboracion.
> 
> ______________________
> 
Hope this helps,
David Warden


More information about the dovecot mailing list