Re: I/O Speed Comparisons

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I guess first question is does the jerky mouse behavior only happen during reads or writes too? How is the CPU utilization in each case?

Mark

On 03/11/2013 01:30 AM, Wolfgang Hennerbichler wrote:
Let me know if I can help out with testing somehow.

Wolfgang
________________________________________
Von: ceph-users-bounces@xxxxxxxxxxxxxx [ceph-users-bounces@xxxxxxxxxxxxxx]" im Auftrag von "Mark Nelson [mark.nelson@xxxxxxxxxxx]
Gesendet: Samstag, 09. März 2013 20:33
Bis: ceph-users@xxxxxxxxxxxxxx
Betreff: Re:  I/O Speed Comparisons

Thanks for all of this feedback guys!  It gives us some good data to try
to replicate on our end.  Hopefully I'll have some time next week to
take a look.

Thanks!
Mark

On 03/09/2013 08:14 AM, Erdem Agaoglu wrote:
Mark,

If it's any help, we've done a small totally unreliable benchmark on our
end. For a KVM instance, we had:
260MB/s write, 200MB/s read on local SAS disks, attached as LVM LVs,
250MB/s write, 90MB/s read on RBD, 32 osds, all SATA.

All sequential, a 10G network. It's more than enough currently but we'd
like to improve RBD read performance.

Cheers,


On Sat, Mar 9, 2013 at 7:27 AM, Andrew Thrift <andrew@xxxxxxxxxxxxxxxxx
<mailto:andrew@xxxxxxxxxxxxxxxxx>> wrote:

     Mark,


     I would just like to add, we too are seeing the same behavior with
     QEMU/KVM/RBD.  Maybe it is a common symptom of high IO with this setup.



     Regards,





     Andrew


     On 3/8/2013 12:46 AM, Mark Nelson wrote:

         On 03/07/2013 05:10 AM, Wolfgang Hennerbichler wrote:



             On 03/06/2013 02:31 PM, Mark Nelson wrote:
             t

                 If you are doing sequential reads, you may benefit by
                 increasing the
                 read_ahead_kb value for each device in
                 /sys/block/<device>/queue on the
                 OSD hosts.


             Thanks, that didn't really help. It seems the VM has to
             handle too much
             I/O, even the mouse-cursor is jerking over the screen when
             connecting
             via vnc. I guess this is the wrong list, but it has somehow
             to do with
             librbd in connection with kvm, as the same machine on LVM
             works just ok.


         Thanks for the heads up Wolfgang.  I'm going to be looking into
         QEMU/KVM
         RBD performance in the coming weeks so I'll try to watch out for
         this
         behaviour.


             Wolfgang
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--
erdem agaoglu



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Mark Nelson
Performance Engineer
Inktank
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