You need to use VirtIO.
<target dev='vdb' bus='virtio'/>
2014/1/10 <steffen.thorhauer@xxxxxxxxxxxxxxxxxxxxxxx>
Hi,
I'm using a 1GBit network. 16 osd on 8 hosts with xfs and journal on ssd.
I have a read performance problem in a libvirt kvm/qemu/rbd VM
on a ceph client host. All involved hosts are ubuntu 13.10. Ceph is 72.2.
The only VM disk is a rbd volume:
<disk type='network' device='disk'>
<driver name='qemu' cache='writeback'/>
<auth username='openstack-control'>
<secret type='ceph' uuid='30f43440-127d-4bf6-ae61-3c0ef03fff39'/>
</auth>
<source protocol='rbd' name='openstack-control/multius'>
<host name='10.37.124.11' port='6789'/>
<host name='10.37.124.12' port='6789'/>
<host name='10.37.124.13' port='6789'/>
</source>
<target dev='hdb' bus='ide'/>
<alias name='ide0-0-1'/>
<address type='drive' controller='0' bus='0' target='0' unit='1'/>
</disk>
The VM uses ext4 filesystem.
Write tests inside the VM shows good performance:
dd if=/dev/zero of=zerofile-2 bs=4M count=2048
2048+0 records in
2048+0 records out
8589934592 bytes (8.6 GB) copied, 78.7491 s, 109 MB/s
But reading the file:
dd if=zerofile-2 of=/dev/null bs=4M count=2048
2048+0 records in
2048+0 records out
8589934592 bytes (8.6 GB) copied, 483.018 s, 17.8 MB/s
bonnie++ shows following:
Version 1.97 ------Sequential Output------ --Sequential Input- --Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
multius 8G 1242 95 105787 27 12331 3 3812 66 23231 3 1561 79
Latency 11801us 851ms 2578ms 239ms 368ms 24062us
Version 1.97 ------Sequential Create------ --------Random Create--------
multius -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 16155us 397us 367us 57us 29us 133us
1.97,1.97,multius,1,1389334826,8G,,1242,95,105787,27,12331,3,3812,66,23231,3,1561,79,16,,,,,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,11801us,851ms,2578ms,239ms,368ms,24062us,16155us,397us,367us,57us,29us,133us
But on the host rados bench with an other rados pool shows good writing and
reading performance:
rados bench -p u124-13 --id u124-13 --keyring=/etc/ceph/client.u124-13.keyring 30 write --no-cleanup
Total writes made: 850
Write size: 4194304
Bandwidth (MB/sec): 111.813
Stddev Bandwidth: 21.4101
Max bandwidth (MB/sec): 124
Min bandwidth (MB/sec): 0
Average Latency: 0.571974
Stddev Latency: 0.260423
Max latency: 2.63825
Min latency: 0.144089
and reading is not so bad:
rados bench -p u124-13 --id u124-13 --keyring=/etc/ceph/client.u124-13.keyring 30 seq
Total reads made: 819
Read size: 4194304
Bandwidth (MB/sec): 106.656
Average Latency: 0.598815
Max latency: 2.25945
Min latency: 0.190397
in my ceph.conf should be cache enabled
[client.openstack-control]
rbd cache = true
rbd cache size = 1073741824
rbd cache max dirty = 536870912
rbd default format = 2
admin socket = /var/run/ceph/rbd-$pid.asok
rbd cache writethrough until flush = true
I guess I misunderstood some configuration options.
Has anybody similiar performance problems?
Regards,
Steffen Thorhauer
--
______________________________________________________________________
Steffen Thorhauer
email: sth@xxxxxxxxxxxxxxxxxxxxxxx
url: http://wwwiti.cs.uni-magdeburg.de/~thorhaue
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