[libvirt] [PATCH] Add --downtime option to virsh migrate command

Matthias Bolte matthias.bolte at googlemail.com
Wed Mar 17 11:22:17 UTC 2010

2010/3/17 Daniel P. Berrange <berrange at redhat.com>:
> On Wed, Mar 17, 2010 at 12:02:27PM +0100, Matthias Bolte wrote:
>> 2010/3/17 Daniel P. Berrange <berrange at redhat.com>:
>> > On Wed, Mar 17, 2010 at 11:05:35AM +0100, Matthias Bolte wrote:
>> >
>> > Conceptually this doesn't make sense. The max downtime parameter is a
>> > live tunable that a management app will set based on the conditions at
>> > the time of migration. Suitable value is dependant on the workload of
>> > the guest (how quickly it is dirtying RAM) and network bandwidth between
>> > hosts (how quickly RAM is transferred). You would only increase the
>> > max downtime if the VM was not able to complete migration promptly
>> > enough. So it shouldn't be persistent, and I don't think there's any
>> > compelling need for a getter either.
>> >
>> > Regards,
>> > Daniel
>> >
>> True. I just had the API POV in mind and forgot about the rest.
>> So we add a new function to configure a per-migration option because
>> we cannot change the existing migrate functions to add a new
>> parameter.
> It isn't sufficient to set this in virDomainMigrate, since it needs to
> be tuned (possibly multiple times) while migration is taking place.
> Regards,
> Daniel

Ah, now I understand how this is supposed to be used and how to it should work!

With that concept in mind the original patch is fine.


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