[Openstack] KVM live block migration: stability, future, docs

Blair Bethwaite blair.bethwaite at gmail.com
Wed Aug 8 00:23:45 UTC 2012


Hi Jay,

On 8 August 2012 06:13, Jay Pipes <jaypipes at gmail.com> wrote:
> Why would you find this surprising? I'm just curious...

The live migration algorithm detailed here:
http://www.linux-kvm.org/page/Migration, seems to me to indicate that
only a brief pause should be expected. Indeed, the summary says,
"Almost unnoticeable guest down time".

But to the contrary. I tested live-migrate (without block migrate)
last night using a guest with 8GB RAM (almost fully committed) and
lost any access/contact with the guest for over 4 minutes - it was
paused for the duration. Not something I'd want to do to a user's
web-server on a regular basis...

> cc'd Daniel Berrange, who seems to be keyed in on upstream KVM/Qemu
> activity. Perhaps Daniel could shed some light.

That would be wonderful. Thanks!

-- 
Cheers,
~Blairo




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