[Dovecot] IO rate quotas?

[Ralf Hildebrandt]

* Timo Sirainen <tss at iki.fi>:
> On Thu, 2011-04-07 at 16:33 +0200, Kádár Tamás (KTamas) wrote:
> 
> > However once in a while, someone goes rogue, we
> > install a new version of thunderbird, someone accidentally sets up an
> > email account in thunderbird mistakingly leaving the download
> > everything option on. This causes high IO on our server, and a single
> > user can quickly more or less kill the whole server in mere minutes,
> > load average quickly spiking to 30-40-50 and everything becomes
> > sloooooow (obviously).
> 
> So a single process that is reading files fast enough from disk can
> cause disk IO to spike in a way that makes all other processes wait for
> available disk IO? I don't think that's a common problem. Typically only
> that one process would be waiting for disk IO and the load would
> increase by 1 (or maybe a little bit more, but definitely not by 50)..
> Maybe you should look into Linux I/O schedulers and see if you're using
> the wrong one.

Sounds like a filesystem problem or a scheduler issue, yes.