Re: [Qemu-devel] [RFC PATCH 0/8] job-based mirroring implementation

[Eric Blake]

On 04/13/2012 12:03 PM, Eric Blake wrote:
> On 04/13/2012 10:23 AM, Paolo Bonzini wrote:
>> Hi all,
>>
>> this is an alternative implementation of mirroring using a block job.
>> In the end this is the same as Marcelo's original live block copy code,
>> only done on top of the job infrastructure and coroutines.  Here, the
>> drive-mirror command sets up a job that copies data using the existing
>> dirty-bitmap functionality.  The target is treated as a "black box"
>> and data is copied from the source to the target in the background.
>>

> 
> - it would be nice to have 'block-job-cancel' as part of 'transaction':
> this would let you take an external copy of multiple disks at the same
> point in time from the perspective of guest execution (right now, you
> can suspend, then do a series of block-job-cancel, then resume the guest
> for the same effect, but how much downtime does that add?)

Given your reply to my question on 8/8, I should be using
'drive-reopen', not 'block-job-cancel', even for reverting to the source
rather than pivoting to the destination.  So one less transactionable
command, and it now becomes a matter of using 'drive-reopen' with the
correct argument depending on which side of the mirror I want qemu to
stick with.

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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