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

From: Jan Kiszka
Subject: [Qemu-devel] Re: [PATCH 0/3 v5] Live migration without shared storage
Date: Mon, 23 Nov 2009 19:47:15 +0100
User-agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv: Gecko/20080226 SUSE/ Thunderbird/ Mnenhy/

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?


Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

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