Re: KVM virtual machines and storage.
On Wed, Jun 13, 2012 at 2:32 PM, Alan Chandler
<alan@chandlerfamily.org.uk> wrote:
>
> I currently run a necessary Windows 7 (Home Premium) installation in a
> VirtualBox virtual machine on my Debian Unstable desktop. Its OK, but I
> have had the occasional glitch when Debian tries to upgrade by kernel
> version and for one reason or another the VirtualBox kernel module hasn't
> kept up.
>
> I would like to migrate to a KVM setup, where the required module is in the
> mainline kernel. I feel that would be safer longer term.
>
> One problem, which I haven't satisfactorily solved so far, is backing up the
> files on the disk in that virtual machine. The best I can do is back up the
> entire file that represents the disk. However the vast majority of that
> disk is not changing on a regular basis and at 120GB of the image in use, it
> takes a lot of resource to back it up. I would much prefer some sort of
> approach that allows me to copy only the recent changes to a rolling
> backup/archive store I have set up for my normal (linux) desktop .
>
> A possibility that occurred to me is that I could make the disk used by the
> virtual machine a raw image file on an LVM logical volume, which I use the
> snapshot capability of to take a frozen snapshot of the disk file at some
> moment in time. Mount that snapshot on the loopback device, so that I get
> to see all the individual files and then back them up. However I am not
> sure that would work, as, I presume, the disk image contains bootsectors and
> stuff like that. Has anyone used this sort of approach, and if so how did
> they get round the issue of device v filesystem.
I'm not sure whether either of these methods'll work with a Windows
filesystem...
1) You can use VB's "shared folder" to copy the files to your host.
2) You can use qemu-nbd to mount a vdi as a loopback device.
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