Re: [libvirt-users] re-create disk image file
On 11/05/2012 02:19 PM, Joe Linoff wrote:
> 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
That sounds like RHEL 6 (or CentOS).
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)
Sounds like one resolved symlinks while the other did not. Maybe it's
worth enhancing libvirt to allow all names that resolve to the same
file, rather than just the exact spelling used? At any rate, we solved
this.
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?
Alas, your qemu is too old. Red Had did not ship live disk snapshots in
RHEL 6.3; to get that functionality, you need RHEV 3.0. Wish I had
better news, but at this point, an in-guest dd to a hot-plugged
alternative disk is the best I can think of, since there's nothing you
can do from the host side without qemu support.
BTW, I tried the dd option with another guest and it seemed to work.
Hope it works for your guest in question, then. Good luck.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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