On 03/11/2013 08:02 AM, Wolfgang Hennerbichler wrote:
also during writes.
I've tested it now on linux with a virtio disk-drive:
<disk type='network' device='disk'>
<driver name='qemu' type='raw'/>
<source protocol='rbd' name='rd/backup:rbd_cache=1'>
<host name='rd-c2.ceph' port='6789'/>
<host name='rd-c1.ceph' port='6789'/>
<host name='wag-c1.ceph' port='6789'/>
</source>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06'
function='0x0'/>
</disk>
virsh console to the running VM.
Next - Write Test:
dd if=/dev/zero of=/bigfile bs=2M &
Serial console gets jerky, VM gets unresponsive. It doesn't crash, but
it's not 'healthy' either. CPU load isn't very high, it's in the waiting
state a lot:
Does this only happen with rbd_cache turned on? If so, it may be the
same cause as http://tracker.ceph.com/issues/3737.
Josh
Cpu(s): 0.0%us, 4.7%sy, 0.0%ni, 26.1%id, 68.4%wa, 0.0%hi, 0.3%si,
0.5%st
1170 root 20 0 11736 2452 556 D 8.5 0.5 0:00.80 dd
Wolfgang
On 03/11/2013 01:42 PM, Mark Nelson wrote:
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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