openstack team mailing list archive

[Scott Moser <smoser@xxxxxxxxxx>]

Can you provide information about what version of kvm you're using ?
I suspect this is really unrelated to openstack specifically.

On Mon, 26 Mar 2012, Martin van Wilderen - JDN BV wrote:

> Hi List,
>
> I have a question about KVM disk performance. We are using Openstack Nova on three machines. These machines have a SSD drive with a dd write performance of about 130mb/s
>
> Within the instance the write performance is down to about 5 mb/s. When using the allocate trick (dd zero to disk before newfs) we get a performance of 20 mb/s.
>
> Things a have tried but don't give any extra results are:
> - Settings the disklayout from qcow2 to raw
> - Settings the cache type in libvirt.xml (writeback, writethrough, none)
> - Switching KSM on and off.
> - Tested with different guests OS, Linux, FreeBSD, Windows.
>
> Is there someone who had some extra info i can check? Or are there more people with this issue?
>
> Snippet from libvirt.xml
> <driver type='qcow2'/ cache='writeback'/>
> <source file='/var/lib/nova/instances/instance-00000113/disk'/>
> <target dev='vda' bus='virtio'/>
>
> Kind regards,
>
> Martin
> _______________________________________________
> Mailing list: https://launchpad.net/~openstack
> Post to     : openstack@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~openstack
> More help   : https://help.launchpad.net/ListHelp
>
>