[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v12 00/11] Drop in_use from BlockDriverState and
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v12 00/11] Drop in_use from BlockDriverState and enable point-in-time snapshot exporting over NBD |
Date: |
Wed, 29 Jan 2014 09:44:28 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Jan 28, 2014 at 08:57:11AM -0800, Ian Main wrote:
> On Tue, Jan 28, 2014 at 03:31:36PM +0100, Stefan Hajnoczi wrote:
> > On Mon, Jan 27, 2014 at 11:48:06AM +0800, Fam Zheng wrote:
> > > This series adds for point-in-time snapshot NBD exporting based on
> > > blockdev-backup (variant of drive-backup with existing device as target).
> > >
> > > We get a thin point-in-time snapshot by COW mechanism of drive-backup, and
> > > export it through built in NBD server. The steps are as below:
> > >
> > > 1. (SHELL) qemu-img create -f qcow2 BACKUP.qcow2 <source size here>
> > >
> > > (Alternatively we can use -o backing_file=RUNNING-VM.img to omit
> > > explicitly
> > > providing the size by ourselves, but it's risky because
> > > RUNNING-VM.qcow2 is
> > > used r/w by guest. Whether or not setting backing file in the image
> > > file
> > > doesn't matter, as we are going to override the backing hd in the next
> > > step)
> > >
> > > 2. (QMP) blockdev-add backing=source-drive file.driver=file
> > > file.filename=BACKUP.qcow2 id=target0 if=none driver=qcow2
> > >
> > > (where source-drive is the running BlockDriverState name for
> > > RUNNING-VM.img. This patch implements "backing=" option to override
> > > backing_hd for added drive)
> > >
> > > 3. (QMP) blockdev-backup device=source-drive sync=none target=target0
> > >
> > > (this is the QMP command introduced by this series, which use a named
> > > device as target of drive-backup)
> > >
> > > 4. (QMP) nbd-server-add device=target0
> > >
> > > When image fleecing done:
> > >
> > > 1. (QMP) block-job-cancel device=source-drive
> > >
> > > 2. (HMP) drive_del target0
> > >
> > > 3. (SHELL) rm BACKUP.qcow2
> >
> > Seems to work as advertized but do you have qemu-iotests for
> > blockdev-backup and image fleecing in particular?
>
> We have them for drive-backup but not blockdev-backup afaik. Mostly the
> same code but certainly a different API.
>
> It shouldn't be too hard to duplicate the 055 drive-backup code and make
> it a blockdev-backup test. Testing nbd export would be difficult
> however.
A Python NBD client is pretty easy to implement. Here is a *server* I
wrote for testing a while back:
https://lists.gnu.org/archive/html/qemu-devel/2013-03/msg01535.html
Stefan
- [Qemu-devel] [PATCH v12 05/11] block: Add bdrv_set_backing_hd(), (continued)
- [Qemu-devel] [PATCH v12 05/11] block: Add bdrv_set_backing_hd(), Fam Zheng, 2014/01/26
- [Qemu-devel] [PATCH v12 06/11] block: Add backing_blocker in BlockDriverState, Fam Zheng, 2014/01/26
- [Qemu-devel] [PATCH v12 07/11] block: Parse "backing" option to reference existing BDS, Fam Zheng, 2014/01/26
- [Qemu-devel] [PATCH v12 08/11] block: Support dropping active in bdrv_drop_intermediate, Fam Zheng, 2014/01/26
- [Qemu-devel] [PATCH v12 09/11] stream: Use bdrv_drop_intermediate and drop close_unused_images, Fam Zheng, 2014/01/26
- [Qemu-devel] [PATCH v12 10/11] qmp: Add command 'blockdev-backup', Fam Zheng, 2014/01/26
- [Qemu-devel] [PATCH v12 11/11] block: Allow backup on referenced named BlockDriverState, Fam Zheng, 2014/01/26
- Re: [Qemu-devel] [PATCH v12 00/11] Drop in_use from BlockDriverState and enable point-in-time snapshot exporting over NBD, Stefan Hajnoczi, 2014/01/28
- Re: [Qemu-devel] [PATCH v12 00/11] Drop in_use from BlockDriverState and enable point-in-time snapshot exporting over NBD, Fam Zheng, 2014/01/28
- Re: [Qemu-devel] [PATCH v12 00/11] Drop in_use from BlockDriverState and enable point-in-time snapshot exporting over NBD, Stefan Hajnoczi, 2014/01/28