[rabbitmq-discuss] rabbitmq causing heavy disk i/o with nothing in the queues
matthias at rabbitmq.com
Thu Jul 11 22:08:58 BST 2013
On 11/07/13 17:38, Kevin Goess wrote:
> Circling back after an earlier question about this problem. We've
> upgraded to 3.1.3-1. We've moved the mnesia files to a dedicated 10k
> sata drive via RABBITMQ_MNESIA_BASE, a new drive that nothing else is
> using, on a xen virtual machine that is only running rabbitmq. We
> generally deal with about 20 messages per second.
> But we're seeing pretty heavy disk activity, with iowait 30-40%, and
> iostat numbers like this:
> Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s
> avgrq-sz avgqu-sz await svctm %util
> xvdbp1 0.00 60.00 0.00 143.40 0.00 1452.80
> 10.13 0.88 6.14 4.22 60.48
> Is this expected? That seems excessive, and I worry that the high
> iowait could cause us problems as we grow, so I was hoping to get some
> pointers to things to look at that to improve that.
My suspicious is that somehow your usage pattern results in a lot of
queue/exchange/binding creation/deletion, which, if the entities
involved are durable, require disk writes and fsyncs.
To test the validity of that theory, please try to find out what files
are seeing activity, and report back.
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