[please don't top-post on technical lists]
Thank you for your suggestions. Here is what happened when I tried
Okay, sorry about that. the
snapshot. I will try the dd a bit later.
VERSIONS virsh: 0.9.10 qemu: 2.0.12
Huh? The current upstream version of qemu is 1.2; I don't recognize the 2.0.12 numbering.
Sorry about that. It was a typo. The version seems to be 0.12.1.2. from running $ /usr/libexec/qemu-kvm --version QEMU PC emulator version 0.12.1 (qemu-kvm-0.12.1.2), Copyright (c) 2003-2008 Fabrice Bellard
DOM: webdev
$ ls -l /proc/13196/fd/9 lrwx------. 1 qemu qemu 64 Nov 5 11:57 /proc/13196/fd/9 -> /tools/vm/images/webdev.img (deleted)
$ cp /proc/13196/fd/9 /tools/vm/images/webdev.img cp: cannot stat `/proc/13196/fd/9': Stale NFS file handle
$ virsh snapshot-create-as webdev \ --no-metadata \ --disk-only \ --diskspec /tools/vm/images/webdev.img,file=/tools/vm/images/webdev.img1 error: unsupported configuration: no disk named '/tools/vm/images/webdev.img'
What does this say?
virsh domblklist webdev
Target Source ------------------------------------------------ vda /var/lib/libvirt/images/webdev.img hdc -
That is the name of the disk where you are creating the snapshot. The --diskspec line needs two pieces of information: a designation for the current file being snapshotted (either the absolute path you used in your xml, or the shorthand name like 'vda' - valid names are found by the domblklist command); and the name of the new file to create the snapshot as.
The fact that your error message complains about "no disk named '/tools/vm/images/webdev.img'" says that you probably didn't spell the file the same as it was named in the XML; seeing the domblklist command will make it clear what name you should be using instead.
I see. Thank you for the clear explanation. It appears that the file name in the XML and the file name referenced by the fd are different: /var/lib/libvirt/images/webdev.img (XML, link, domblklist) /tools/vm/images/webdev.img (filer, fd reference) I modified the command to use /var/lib/libvirt/images/webdev.img but it had a different problem: # virsh snapshot-create-as webdev \ --no-metadata \ --disk-only \ --diskspec /var/lib/libvirt/images/webdev.img,file=/tools/vm/images/webdev.img1 error: operation failed: Failed to take snapshot: unknown command: 'snapshot_blkdev' I don't understand what the message is trying to tell me. Why would snapshot_blkdev not be available? Perhaps the version I have is too old?
# Pull the contents into the new file virsh blockpull $dom /tmp/guest.img1 --wait --verbose
For the blockpull command, the same usage applies - you name the disk by its path (but note that you just changed the path as a result of the snapshot-create-as command; as another domblklist would prove) or by its > device name, such as vda.
I see. BTW, I tried the dd option with another guest and it seemed to work. Thank you, Joe -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org