[libvirt-users] VM with transient disk
I want to use transient disks with libvirt. According to [1], the transient disk feature has been supported since 0.9.5. Hence, I have installed libvirt 0.9.6 for Ubuntu Lucid from [2] and used the following disk configuration: <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/home/till/test.img'/> <target dev='vda' bus='virtio'/> <transient/> </disk> However, I get: unsupported configuration: transient disks not supported yet Best, Till [1] http://libvirt.org/formatdomain.html [2] http://ppa.launchpad.net/agent-8131/xen-custom/ubuntu/
On 10/31/2011 03:18 AM, Till Mossakowski wrote:
I want to use transient disks with libvirt. According to [1], the transient disk feature has been supported since 0.9.5. Hence, I have installed libvirt 0.9.6 for Ubuntu Lucid from [2] and used the following disk configuration:
<disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/home/till/test.img'/> <target dev='vda' bus='virtio'/> <transient/> </disk>
However, I get: unsupported configuration: transient disks not supported yet
That's because libvirt supported it yet, but qemu still haven't complete the support. Not sure if the newest upstream qemu already supported it though. Osier
Hi Osier, are there other hypervisors supporting it? And what about qemu's option "snapshot=on" ? Best, Till Am 31.10.2011 04:28, schrieb Osier Yang:
On 10/31/2011 03:18 AM, Till Mossakowski wrote:
I want to use transient disks with libvirt. According to [1], the transient disk feature has been supported since 0.9.5. Hence, I have installed libvirt 0.9.6 for Ubuntu Lucid from [2] and used the following disk configuration:
<disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/home/till/test.img'/> <target dev='vda' bus='virtio'/> <transient/> </disk>
However, I get: unsupported configuration: transient disks not supported yet
That's because libvirt supported it yet, but qemu still haven't complete the support. Not sure if the newest upstream qemu already supported it though.
Osier
On 10/31/2011 12:54 AM, Till Mossakowski wrote:
Hi Osier,
are there other hypervisors supporting it?
Not yet. It was added to the XML with intents to support it in at least ESX and qemu, but neither driver has completed this support of the XML yet. And it looks like 0.9.7 won't have it either, now that we are in feature freeze for the next release. I'll get to it eventually, but I would welcome anyone else trying to contribute patches in the meantime, since I have been distracted by bug fixes lately (fixing any existing but broken behavior tends to take priority over implementing new behavior).
And what about qemu's option "snapshot=on" ?
Unreliable. It won't work with SELinux (since qemu tries to create the snapshot on /tmp), and it makes your guest unmigratable. I think that it is easier to have libvirt use qemu-img to create a qcow2 wrapper prior to booting the guest, at which point the solution is easier to control from an sVirt perspective, and is more likely to allow us to figure out a way to make things work with migration (at least, I'm hoping I can figure out how to migrate a guest with a transient disk). But if you want to use qemu's snapshot=on in the meantime, you can use the <qemu:commandline> namespace XML to add it. -- Eric Blake eblake@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
participants (3)
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Eric Blake -
Osier Yang -
Till Mossakowski