Hi David, 1. Yes. That's the only disk in the system.
2. Yes: nova1:/var/lib/nova/instances$ dd if=/dev/zero of=test bs=1M count=256 256+0 records in 256+0 records out 268435456 bytes (268 MB) copied, 2.04146 s, 131 MB/s 4. I have tried with: - Linux Ubuntu 10.10 - FreeBSD 8.2 with virtio driver - Windows 2008 R2 Server with virtio driver 3. my libvirt.xml <domain type='kvm'> <name>instance-00000121</name> <memory>1048576</memory> <os> <type>hvm</type> <boot dev="hd" /> </os> <features> <acpi/> </features> <vcpu>2</vcpu> <devices> <disk type='file'> <driver type='raw'/> <source file='/var/lib/nova/instances/instance-00000121/disk'/> <target dev='vda' bus='virtio'/> </disk> <disk type='file'> <driver type='raw'/> <source file='/var/lib/nova/instances/instance-00000121/disk.local'/> <target dev='vdb' bus='virtio'/> </disk> <interface type='bridge'> <source bridge='br100'/> <mac address='02:16:3e:33:42:e3'/> <filterref filter="nova-instance-instance-00000121-02163e3342e3"> <parameter name="IP" value="10.0.0.34" /> <parameter name="DHCPSERVER" value="10.0.0.9" /> </filterref> </interface> <!-- The order is significant here. File must be defined first --> <serial type="file"> <source path='/var/lib/nova/instances/instance-00000121/console.log'/> <target port='1'/> </serial> <console type='pty' tty='/dev/pts/2'> <source path='/dev/pts/2'/> <target port='0'/> </console> <serial type='pty'> <source path='/dev/pts/2'/> <target port='0'/> </serial> <graphics type='vnc' port='-1' autoport='yes' keymap='en-us' listen='0.0.0.0'/> </devices> </domain> Met vriendelijke groet, Martin van Wilderen Technical Manager On Mar 26, 2012, at 4:45 PM, David Busby wrote: > Hi Martin > > Does /var/lib/nova/instances reside on your SSD? (just double checking it's > not instead pointing to a normal stoage device). > Do you see the expected performance on the host operating system? > Could you please provide the complete libvirt .xml file? > Could you please provide the operating system and version of the guest? > > Cheers > > David > > > > On Mon, Mar 26, 2012 at 1:59 PM, Martin van Wilderen - JDN BV <mar...@jdn.nl> > 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@lists.launchpad.net > Unsubscribe : https://launchpad.net/~openstack > More help : https://help.launchpad.net/ListHelp >
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