Re: Strange write behavior on an osd

["João Eduardo Luís" <jecluis@gmail.com>]

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On 04/24/2012 03:32 PM, Martin Mailand wrote:
> Hi,
> I have a strange behavior on the osd, the cluster is a two node system,
> on one machine 50 qemu/rbd vm's are running (idling) the other machine
> is a osd with four osd processes and one mon processes.
> 
> The osd disk are as follow
> 
> sda is root
> sdb is journal four partitions
> sd{c,d,e,f) each three disk via a raid controler.
> 
> /dev/sdc on /data/osd.0 type btrfs
> (rw,noatime,nodiratime,nodatacow,autodefrag)
> /dev/sdd on /data/osd.1 type btrfs
> (rw,noatime,nodiratime,nodatacow,autodefrag)
> /dev/sde on /data/osd.2 type btrfs
> (rw,noatime,nodiratime,nodatacow,autodefrag)
> /dev/sdf on /data/osd.3 type btrfs
> (rw,noatime,nodiratime,nodatacow,autodefrag)
> 
> 
> There is almost no network traffic, but the osd writes huge amount to
> the disk for around 90 sec and then its almost idle for 30 sec, the
> writes always goes to sde.
> 
> Why is it so bursty?
> 
> [snip]

Any chance you could run iotop during the busy periods and tell us which
processes are issuing the io?

-- 
João Eduardo Luís
gpg key: 477C26E5 from pool.keyserver.eu


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