From: Fam Zheng <famz@redhat.com>
To: Zhang Haoyu <zhanghy@sangfor.com.cn>
Cc: Kevin Wolf <kwolf@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
vsementsov <vsementsov@parallels.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>, jsnow <jsnow@redhat.com>
Subject: Re: [Qemu-devel] [RFC] introduce bitmap to bdrv_commit to track dirty sector
Date: Tue, 10 Mar 2015 08:28:41 +0800 [thread overview]
Message-ID: <20150310002841.GA28815@ad.nay.redhat.com> (raw)
In-Reply-To: <201503091614373394821@sangfor.com.cn>
On Mon, 03/09 16:14, Zhang Haoyu wrote:
> Hi John, Vladimir
> We can using active block commit to implement incremental backup without guest disruption,
> e.g.,
> origin <= A <= B <= C <= current BDS,
> a new external snapshot will be produced before every time backup,
> we can migrate A, B, C, ... to destination,
> then commit_active_start() the unneeded snapshot in source or destination end.
>
> So, comparing with above mechanism,
> what's the advantages of the incremental backup implemented by John and Vladimir?
We can't migrate A, B, C because they are buried in the backing chain under
"current BDS". Even if we do that, there will be severe IO amplification
compared to the dirty bitmap way.
For the same reason we have drive-backup (write intercept) instead of a
"snapshot + drive-mirror" analogue.
Fam
next prev parent reply other threads:[~2015-03-10 0:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-03 6:52 [Qemu-devel] [RFC] introduce bitmap to bdrv_commit to track dirty sector Zhang Haoyu
2015-03-03 9:59 ` Paolo Bonzini
2015-03-09 7:03 ` Zhang Haoyu
2015-03-09 7:38 ` Paolo Bonzini
2015-03-09 8:14 ` Zhang Haoyu
2015-03-10 0:28 ` Fam Zheng [this message]
2015-03-10 1:30 ` [Qemu-devel] [RFC] introduce bitmap to bdrv_commit to trackdirty sector Zhang Haoyu
2015-03-10 1:54 ` Fam Zheng
2015-03-10 2:12 ` [Qemu-devel] [RFC] introduce bitmap to bdrv_commit to trackdirtysector Zhang Haoyu
2015-03-10 2:58 ` Fam Zheng
2015-03-10 3:12 ` [Qemu-devel] [RFC] introduce bitmap to bdrv_commit totrackdirtysector Zhang Haoyu
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