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Re: KVM disk performance


Have you tried virtio for storage?


Enviado desde mi iPhone, perdona la brevedad

El 26/03/2012, a las 14:59, Martin van Wilderen - JDN BV <martin@xxxxxx> escribió:

> 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
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