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> 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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