Re: [Qemu-devel] QEMU detachable overlays and Union Mounts

[kausik pal]

Hi rich,

Thanks for the answer.

I was wondering how unidesk has solved the problem using disk layering. They have the solution for VMware, so if similar feature can be built on qemu for KVM hypervisor then we will have a great solution for application management from VDI perspective.

Please let me know your thought about this.

Thanks
Kausik

On Jan 8, 2014 11:11 PM, "Richard W.M. Jones" <address@hidden> wrote:

On Wed, Jan 08, 2014 at 11:26:28AM +0530, kausik pal wrote:
> If this message should go elsewhere, my apologies.
>
> It would be great if QEMU have the capability of detachable overlay or
> union mount.
> So administrators can keep each software as separate individual qcow2/qed
> disks and can put those disks on different layers so that the end user
> would see combination of the softwares available to them.
>
> The desired scenario is like the following:-

[easier to see the diagrams here:
https://lists.gnu.org/archive/html/qemu-devel/2014-01/msg00819.html]

qemu already supports snapshots.  However they don't work like docker,
ie. you cannot arbitrarily compose snapshots (I don't think this works
properly in docker either, but that's another matter).

Basically because snapshots are block-based, not file based, it is
never going to be possible to compose them in the way you want.
Filesystems at the block layer simply don't work this way.

Have you considered using 9p? [http://wiki.qemu.org/Documentation/9psetup]

Rich.

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