* [Qemu-devel] [migration] questions about removing the old block-migration code
@ 2013-11-03 4:01 Zhanghaoyu (A)
2013-11-05 13:34 ` Stefan Hajnoczi
0 siblings, 1 reply; 4+ messages in thread
From: Zhanghaoyu (A) @ 2013-11-03 4:01 UTC (permalink / raw)
To: quintela@redhat.com
Cc: Huangweidong (C), Michael S. Tsirkin, Michal Privoznik,
Marcelo Tosatti, paolo.bonzini@gmail.com, qemu-devel@nongnu.org,
Xiahai, Linqiangmin, Zanghongyong, Luonengjun, Huangpeng (Peter)
Hi, Juan
I read below words on the report of <KVM Live Migration: Weather forecast (May 29, 2013)>,
We were going to remove the old block-migration code
Then people fixed it
Good: it works now
Bad: We have to maintain both
It uses the same port than migration
You need to migrate all/none of block devices
The old block-migration code said above is that in block-migration.c?
What are the reasons of removing the old block-migration code? Buggy implementation? Or need to migrate all/none of block devices?
What's the substitutional method? drive_mirror?
Thanks,
Zhang Haoyu
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [migration] questions about removing the old block-migration code
2013-11-03 4:01 [Qemu-devel] [migration] questions about removing the old block-migration code Zhanghaoyu (A)
@ 2013-11-05 13:34 ` Stefan Hajnoczi
2013-11-08 1:17 ` Zhanghaoyu (A)
0 siblings, 1 reply; 4+ messages in thread
From: Stefan Hajnoczi @ 2013-11-05 13:34 UTC (permalink / raw)
To: Zhanghaoyu (A)
Cc: Huangweidong (C), Michael S. Tsirkin, Michal Privoznik,
Linqiangmin, Marcelo Tosatti, paolo.bonzini@gmail.com,
qemu-devel@nongnu.org, Xiahai, quintela@redhat.com, Zanghongyong,
Luonengjun, Huangpeng (Peter)
On Sun, Nov 03, 2013 at 04:01:36AM +0000, Zhanghaoyu (A) wrote:
> I read below words on the report of <KVM Live Migration: Weather forecast (May 29, 2013)>,
> We were going to remove the old block-migration code
> Then people fixed it
> Good: it works now
> Bad: We have to maintain both
> It uses the same port than migration
> You need to migrate all/none of block devices
>
> The old block-migration code said above is that in block-migration.c?
Yes.
> What are the reasons of removing the old block-migration code? Buggy implementation? Or need to migrate all/none of block devices?
Buggy and tightly coupled with the live migration code, making it hard
to modify either area independently.
> What's the substitutional method? drive_mirror?
drive_mirror over NBD is an alternative. There are security and
integration challenges with those approaches but libvirt has added
drive-mirror block migration support.
Stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [migration] questions about removing the old block-migration code
2013-11-05 13:34 ` Stefan Hajnoczi
@ 2013-11-08 1:17 ` Zhanghaoyu (A)
2013-11-15 15:33 ` Stefan Hajnoczi
0 siblings, 1 reply; 4+ messages in thread
From: Zhanghaoyu (A) @ 2013-11-08 1:17 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Huangweidong (C), quintela@redhat.com, Michael S. Tsirkin,
Michal Privoznik, Marcelo Tosatti, paolo.bonzini@gmail.com,
qemu-devel@nongnu.org, Xiahai, Linqiangmin, Zanghongyong,
Luonengjun, Huangpeng (Peter)
>> I read below words on the report of <KVM Live Migration: Weather
>> forecast (May 29, 2013)>, We were going to remove the old
>> block-migration code Then people fixed it
>> Good: it works now
>> Bad: We have to maintain both
>> It uses the same port than migration
>> You need to migrate all/none of block devices
>>
>> The old block-migration code said above is that in block-migration.c?
>
>Yes.
>
>> What are the reasons of removing the old block-migration code? Buggy implementation? Or need to migrate all/none of block devices?
>
>Buggy and tightly coupled with the live migration code, making it hard to modify either area independently.
Thanks a lot for explaining.
Till now, we still use the old block-migration code in our virtualization solution.
Could you detail the bugs that the old block-migration code have?
Thanks,
Zhang Haoyu
>
>> What's the substitutional method? drive_mirror?
>
>drive_mirror over NBD is an alternative. There are security and integration challenges with those approaches but libvirt has added drive-mirror block migration support.
>
>Stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [migration] questions about removing the old block-migration code
2013-11-08 1:17 ` Zhanghaoyu (A)
@ 2013-11-15 15:33 ` Stefan Hajnoczi
0 siblings, 0 replies; 4+ messages in thread
From: Stefan Hajnoczi @ 2013-11-15 15:33 UTC (permalink / raw)
To: Zhanghaoyu (A)
Cc: Huangweidong (C), quintela@redhat.com, Michael S. Tsirkin,
Michal Privoznik, Marcelo Tosatti, paolo.bonzini@gmail.com,
qemu-devel@nongnu.org, Xiahai, Linqiangmin, Zanghongyong,
Luonengjun, Huangpeng (Peter)
On Fri, Nov 08, 2013 at 01:17:17AM +0000, Zhanghaoyu (A) wrote:
> >> I read below words on the report of <KVM Live Migration: Weather
> >> forecast (May 29, 2013)>, We were going to remove the old
> >> block-migration code Then people fixed it
> >> Good: it works now
> >> Bad: We have to maintain both
> >> It uses the same port than migration
> >> You need to migrate all/none of block devices
> >>
> >> The old block-migration code said above is that in block-migration.c?
> >
> >Yes.
> >
> >> What are the reasons of removing the old block-migration code? Buggy implementation? Or need to migrate all/none of block devices?
> >
> >Buggy and tightly coupled with the live migration code, making it hard to modify either area independently.
>
> Thanks a lot for explaining.
> Till now, we still use the old block-migration code in our virtualization solution.
> Could you detail the bugs that the old block-migration code have?
Please use git log block-migration.c to see bugs that have been fixed.
The basic problem is that block-migration.c hasn't been actively
maintained or used much. My impression is that the newer block
migration approach using drive-mirror now has more developer and testing
focus (see libvirt if you're curious how drive-mirror can be
orchestrated).
Stefan
^ permalink raw reply [flat|nested] 4+ messages in thread
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2013-11-03 4:01 [Qemu-devel] [migration] questions about removing the old block-migration code Zhanghaoyu (A)
2013-11-05 13:34 ` Stefan Hajnoczi
2013-11-08 1:17 ` Zhanghaoyu (A)
2013-11-15 15:33 ` Stefan Hajnoczi
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