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Date: Tue, 10 Mar 2015 10:01:34 +0800
From: "Zhang Haoyu" <zhanghy@sangfor.com.cn>
References: <201501130948157439113@sangfor.com.cn>,
	<201501131002532239699@sangfor.com.cn>,
	<201501141041046517018@sangfor.com.cn>,
	<201501141558472151450@sangfor.com.cn>,
	<201501151154417870577@sangfor.com.cn>,
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Message-ID: <201503101001341072349@sangfor.com.cn>
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Subject: Re: [Qemu-devel] question about live migration with storage
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To: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel <qemu-devel@nongnu.org>
Cc: Gleb Natapov <gleb@kernel.org>, Stefan Hajnoczi <stefanha@redhat.com>


On 2015-01-15 18:08:39, Paolo Bonzini wrote:
> 
> On 15/01/2015 10:56, Zhang Haoyu wrote:
> > I see, when waiting the completion of drive_mirror IO, the coroutine will be
> > switched back to main-thread to poll and process other events, like qmp request,
> > then after the IO completed, coroutine will be switched back in main-loop process, right?
> > 
> > Another question:
> > while starting to migrate storage, will the unused sector be allocated and transferred?
> > regarding the thin-provisioning qcow2 disk, will extra large IO requests be
> > performed, and more data be transferred for the unallocated clusters?
> 
> No.
> 
My test results show that
when using thin-provisioning qcow2 image(created by qemu-img create -f qcow2 preallocation=metadata),
even the unallocated sectors will be transferred to destination, so much data is transferred,
so the qcow2 image in destination is full allocated.

Thanks,
Zhang Haoyu
> Paolo