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Re: [Qemu-devel] Re: [PATCH 0/3 v5] Live migration without shared storag

From: Pierre Riteau
Subject: Re: [Qemu-devel] Re: [PATCH 0/3 v5] Live migration without shared storage
Date: Tue, 24 Nov 2009 15:11:32 +0100

On 23 nov. 2009, at 19:47, Jan Kiszka wrote:

> Avi Kivity wrote:
>> On 11/03/2009 11:40 AM, Liran Schour wrote:
>>> - Liran
>>> Avi Kivity<address@hidden>  wrote on 02/11/2009 20:47:34:
>>>> On 11/02/2009 03:40 PM, address@hidden wrote:
>>>>> This series adds support for live migration without shared storage,
>>> means
>>>>> copy the storage while migrating. It was tested with KVM. Supports 2
>>> ways
>>>>> to replicate the storage during migration:
>>>>> 1. Complete copy of storage to destination
>>>>> 2. Assuming the storage is cow based, copy only the allocated
>>>>> data, time of the migration will be linear with the amount of allocated
>>>>> data (user responsibility to verify that the same backend file reside
>>>>> on src and destination).
>>>>> Live migration will work as follows:
>>>>> (qemu) migrate -d tcp:0:4444 # for ordinary live migration
>>>>> (qemu) migrate -d blk tcp:0:4444 # for live migration with
>>>> complete storage copy
>>>>> (qemu) migrate -d blk inc tcp:0:4444 # for live migration with
>>>> incremental storage copy, storage is cow based.
>>>> I'd like to see the syntax generalized.  For one, the guest may have
>>>> several disks; an install image cdrom might be available as an nfs image
>>>> but the main storage is local.  Secondly, there can be several levels of
>>>> cow and we want to control which one we copy.
>>>> I'll leave the exact details to the qpeople, but if we can specify a
>>>> copy depth for each device, where 0=copy nothing, n=copy everything,
>>>> 1=copy the last level (equivalent to -d blk inc) I think we'll have
>>>> covered everything.
>>> I propose the following syntax:
>>> migrate [-d] [-b [<device:copy_level>  ...<device:copy_level>]]
>>> tcp:<host>:<port>
>>> Where device will be the name of the device: ide0-hd0. And copy_level
>>> will
>>> be integer or n, 0=flat copy of the device, 1=copy the last level ...
>>> n=copy all levels.
>>> All HD devices that will not appear in the command will be treated as
>>> copy_level=0. All devices != BDRV_TYPE_HD will be ignored.
>> Looks good.
> Do I get this correctly: this series is now "only" blocked by the
> required rework of its user interface? Is there a schedule for this, a
> v6 roll out? Will it be in time for qemu-0.12?
> Jan

It was committed to the master branch a week ago.

Pierre Riteau -- http://perso.univ-rennes1.fr/pierre.riteau/

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