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Re: [Qemu-devel] [PATCH v14 7/8] Implement new driver for block replicat
From: |
Wen Congyang |
Subject: |
Re: [Qemu-devel] [PATCH v14 7/8] Implement new driver for block replication |
Date: |
Mon, 1 Feb 2016 09:13:36 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 01/29/2016 11:46 PM, Stefan Hajnoczi wrote:
> On Fri, Jan 29, 2016 at 11:13:42AM +0800, Changlong Xie wrote:
>> On 01/28/2016 11:15 PM, Stefan Hajnoczi wrote:
>>> On Thu, Jan 28, 2016 at 09:13:24AM +0800, Wen Congyang wrote:
>>>> On 01/27/2016 10:46 PM, Stefan Hajnoczi wrote:
>>>>> On Wed, Jan 13, 2016 at 05:18:31PM +0800, Changlong Xie wrote:
>>> I'm concerned that the bdrv_drain_all() in vm_stop() can take a long
>>> time if the disk is slow/failing. bdrv_drain_all() blocks until all
>>> in-flight I/O requests have completed. What does the Primary do if the
>>> Secondary becomes unresponsive?
>>
>> Actually, we knew this problem. But currently, there seems no better way to
>> resolve it. If you have any ideas?
>
> Is it possible to hold the checkpoint information and acknowledge the
> checkpoint right away, without waiting for bdrv_drain_all() or any
> Secondory guest activity to complete?
There is no way to know that secondary becomes unreponsive.
>
> I think this really means falling back to microcheckpointing until the
> Secondary guest can checkpoint. Instead of a blocking vm_stop() we
> would prevent vcpus from running and when the last pending I/O finishes
> the Secondary could apply the last checkpoint. This approach does not
> block QEMU (the monitor, etc).
>
If secondary host becomes unresponsive, it means that we cannot do
mocrocheckpointing.
We should do failover in this case.
Thanks
Wen Congyang
- [Qemu-devel] [PATCH v14 1/8] unblock backup operations in backing file, (continued)
[Qemu-devel] [PATCH v14 2/8] Store parent BDS in BdrvChild, Changlong Xie, 2016/01/13
[Qemu-devel] [PATCH v14 8/8] support replication driver in blockdev-add, Changlong Xie, 2016/01/13
[Qemu-devel] [PATCH v14 3/8] Backup: clear all bitmap when doing block checkpoint, Changlong Xie, 2016/01/13
[Qemu-devel] [PATCH v14 4/8] Allow creating backup jobs when opening BDS, Changlong Xie, 2016/01/13
[Qemu-devel] [PATCH v14 5/8] docs: block replication's description, Changlong Xie, 2016/01/13
Re: [Qemu-devel] [PATCH v14 0/8] Block replication for continuous checkpoints, Changlong Xie, 2016/01/13