Re: [Qemu-devel] [PATCH V4 0/3] Block migration if any of the block device is busy

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Jul 24, 2012 at 10:52 AM, Kevin Wolf <kwolf@redhat.com> wrote:
> Am 23.07.2012 16:22, schrieb benoit.canet@gmail.com:
>> From: Benoît Canet <benoit@irqsave.net>
>>
>> This patchset is designed to avoid starting a live migration while any of
>> the block device is busy.
>>
>> Tested with the following sequence:
>>
>> QEMU 1.1.50 monitor - type 'help' for more information
>> (qemu) block_stream virtio0 1k
>> (qemu) migrate tcp:localhost:4444
>> migrate: Migration is blocked by streaming
>> (qemu)  block_job_cancel virtio0
>> (qemu)  migrate tcp:localhost:4444
>> migrate: Connection can not be completed immediately
>> (qemu)
>> => migration then succeed
>
> Maybe I'm missing the obvious, but why? Migration will stop the
> streaming if it isn't restarted explicitly on the destination, but I
> think that's expected.

Hmm...maybe this is a policy decision.  I figure if you are running
image streaming and try to migrate, chances are you're migration will
break on the destination host because you were trying to do pre-copy
storage migration and never finished.

Stefan