[Dovecot] IO rate quotas?

Robert Schetterer robert at schetterer.org
Fri Apr 8 18:21:00 EEST 2011

Am 08.04.2011 15:53, schrieb 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.

perhaps try

echo "deadline" > /sys/block/sda/queue/scheduler

Best Regards

MfG Robert Schetterer


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