Re: [Qemu-devel] [migration] questions about removing the old block-migration code

[Zhanghaoyu (A)]

>> 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