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Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu |
Date: |
Thu, 21 Feb 2013 14:08:27 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Feb 20, 2013 at 04:04:49PM +0000, Dietmar Maurer wrote:
> > Interesting series, the backup block job makes sense to me. Regarding
> > efficiency, I think incremental backup is a must, otherwise regular backups
> > using this approach won't really be a win over backing files.
>
> Incremental backup is something different, not touched by this code.
> You can add that later if needed.
>
> > The backup writer abstraction is a special case interface somewhere
> > between an image format and live migration. I'd prefer it if the backup
> > block job stuck to BlockDriverState as the destination for backup data.
> > Then you could save a point-in-time copy of a disk to a raw or even
> > qcow2 image.
>
> backup needs to work on non-seekable pipes.
>
> > The vmstate feature looks like vmsave duplication. The problem with
> > vmsave is that it doesn't compose nicely with block jobs or the QMP
> > transaction command, which would allow you to snapshot the disks and
> > then capture the VM state.
> >
> > How would VMA fit in if the backup block job took a BlockDriverState
> > destination and vmsave worked atomically with backup block jobs? You
> > could have QEMU write to NBD server ports that a VMA writer process has
> > open. VMA would happen outside the QEMU process.
>
> We want to write to pipes, so what you suggest simply does not work?
Writing to pipes still works, the data is just passed first to a process
on the host which writes the archive to the pipe. The archive write
process writes to the pipe, not QEMU.
Stefan
Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Stefan Hajnoczi, 2013/02/20
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Dietmar Maurer, 2013/02/20
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu,
Stefan Hajnoczi <=
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Kevin Wolf, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Dietmar Maurer, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Paolo Bonzini, 2013/02/21
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Stefan Hajnoczi, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Kevin Wolf, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Stefan Hajnoczi, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Paolo Bonzini, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Dietmar Maurer, 2013/02/22
- Re: [Qemu-devel] [PATCH v4 0/6] Efficient VM backup for qemu, Paolo Bonzini, 2013/02/22