RE: Unable to start VM using COWed image

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> From: Stefan Hajnoczi [stefanha@xxxxxxxxx]
> Sent: 10 November 2010 12:47
> To: Prasad Joshi
> Cc: Keqin Hong; kvm@xxxxxxxxxxxxxxx
> Subject: Re: Unable to start VM using COWed image

> On Wed, Nov 10, 2010 at 12:40 PM, Prasad Joshi
<P.G.Joshi@xxxxxxxxxxxxxxxxxxxxx> wrote:
>> From: Stefan Hajnoczi [stefanha@xxxxxxxxx]
>> Sent: 10 November 2010 11:12
>> To: Prasad Joshi
>> Cc: Keqin Hong; kvm@xxxxxxxxxxxxxxx
>> Subject: Re: Unable to start VM using COWed image
>
> On Wed, Nov 10, 2010 at 10:08 AM, Prasad Joshi
> <P.G.Joshi@xxxxxxxxxxxxxxxxxxxxx> wrote:
>> Where can I get the code of the qemu-kvm program?
>> I cloned the qemu-lvm git repository and compiled the code. But it looks like qemu-kvm program is not part of this code.--
>
>> qemu-kvm.git contains the qemu-kvm codebase but the binary is built in
>> x86_64-softmmu/qemu-system-x86_64.  Distro packages typically rename
>> it to qemu-kvm.
>
> Thanks Stefan for your reply.
>
> I guess you pointed out the problem in the first mail. QEMU places a restriction on location of the COWed file. The source image and COWed image should be in the same drectory.
>
> In my case the source image was in directory /var/lib/libvirt/images/ and the COWed image was in /home/prasad/Virtual directory.
> While debuging the source code using gdb I realized this limitation. It would be good to fix this problem. I will see if I can solve this problem.

> This behavior is a feature.  You chose to use a relative backing file
> path when you used qemu-img create -b <relative-path>.

> If you want an absolute path you need to use qemu-img create -b
> /home/prasad/Virtual/... (i.e. specify an absolute path instead of a
> relative path).

Oh I  see. I am such a stupid. ha ha ha ha
Thanks a lot for letting me know.
It worked after using absolute paths. Gr8 Thanks a lot.

>> One more question on the same lines,
>> How does QEMU detect the file is COWed and the name of the file (not whole path) from it is COWed?

> COW support comes from the image file format that you choose.  A qcow
> file is not just a raw image file like the kind you can dd from a real
> disk.  Instead it has its own file format including a header and
> metadata for tracking allocated space.  The header contains the name
> of the backing file.

> Stefan
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux