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Re: [Qemu-devel] [RFC PATCH 0/3] Point-in-time snapshot exporting with d
Re: [Qemu-devel] [RFC PATCH 0/3] Point-in-time snapshot exporting with drive-backup
Wed, 26 Jun 2013 15:31:19 +0800
On Wed, 06/26 09:23, Paolo Bonzini wrote:
> Il 26/06/2013 05:59, Fam Zheng ha scritto:
> > The block job originally had total control over target bs: when the job
> > completes, the target is deleted. Now it's shared with NBD, so we should
> > make
> > sure the job completion or canceling wouldn't crash NBD server. This patch
> > doesn't handle this case: if the block job is ended before NBD exporting,
> > there'll be problem.
> This should not be a problem. When the job completes or cancels it will
> close s->target. The NBD server has installed a close notifier for
> s->target, and will close connections with the clients.
> Similarly, if the source disk is hot-unplugged, the bdrv_close will
> cancel the job, which in turn closes connections with the clients.
> So this just works as long as no hot-unplug happens and as long as the
> job doesn't complete: the client can use the point-in-time snapshot via
> NBD as long as it cares to.
OK, thanks for pointing this out.
> This leads to another observation: a sync:'none' block-backup job
> probably should never complete, and should instead go on until explicit
> cancellation. This is because the job does no background writes, and
> thus completion would only happen after the guest has written the whole
> disk. Writing the whole disk is rare enough that it will likely cause
> bugs in the clients. It is easier just to never complete the job.
Yes, the sync mode none will simply run forever until cancelled.
[Qemu-devel] [RFC PATCH 2/3] block: assign backing relationship in drive-backup, Fam Zheng, 2013/06/26
[Qemu-devel] [RFC PATCH 3/3] nbd: don't get ref if bs has no drive, Fam Zheng, 2013/06/26
Re: [Qemu-devel] [RFC PATCH 0/3] Point-in-time snapshot exporting with drive-backup, Paolo Bonzini, 2013/06/26
- [Qemu-devel] [RFC PATCH 1/3] block: add target-id option to drive-backup QMP command, (continued)
- Re: [Qemu-devel] [RFC PATCH 0/3] Point-in-time snapshot exporting with drive-backup,
Fam Zheng <=