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@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
