2014-06-13 22:04 GMT+08:00 Andrey Korolyov <and...@xdel.ru>:
>
> On Fri, Jun 13, 2014 at 5:50 PM, Ke-fei Lin <k...@kfei.net> wrote:
> > Thanks, Andrey.
> >
> > I tried `virsh domblkstat <vm> hda` (only this VM in whole cluster) and
got
> > these values:
> >
> > hda rd_req 70682
> > hda rd_bytes 229894656
> > hda wr_req 1067
> > hda wr_bytes 12645888
> > hda flush_operations 0
> >
> > (These values became stable after ~2 mins)
> >
> > While the output of `ceph -w` is attached at:
http://pastebin.com/Uhdj9drV
> >
> > Any advices?
>
>
> Thanks, poor man`s analysis shows that it can be true - assuming
> median heartbeat value as 1.2s, overall read ops are about 40k, which
> is close enough to what qemu stats saying, regarding floating
> heartbeat interval. Because ceph -w never had such value as a precise
> measurement tool, I may suggest to measure block stats difference on
> smaller intervals, about 1s or so, and compare values then. By the
> way, what driver do you use in qemu for a block device?
OK, this time I capture the blkstat difference in a smaller interval (less
than 1s).
And a simple calculation gives me some result:
(19531264-19209216)/(38147-37518) = 512
...
(20158976-19531264)/(39373-38147) = 512
Which means in the beginning of boot phase, every read request from VM is
just *512 byte*.
Maybe this is why `ceph -w` shows me every operation is about 1KB (in my
first post)?
So seems this is the inherent problem of Windows VM, but can I do something
in my Ceph
cluster's configuration to improve this?
By the way the related part of my VM definition are:
<emulator>/usr/bin/kvm</emulator>
<disk type='network' device='disk'>
<driver name='qemu' type='rbd' cache='writeback'/>
<source protocol='rbd' name='libvirt-pool/test-rbd-1'>
<host name='10.0.0.5' port='6789'/>
</source>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' unit='0'/>
</disk>
Thanks.
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