Open Stack

Thanks for the clarification Daniel

Razique Mahroua - Nuage & Co
razique.mahroua at gmail.com
Tel : +33 9 72 37 94 15



Le 24 avr. 2013 à 17:59, "Daniel P. Berrange" <dan at berrange.com> a écrit :

> On Wed, Apr 24, 2013 at 11:48:35AM -0400, Lorin Hochstein wrote:
>> In the docs, we describe how to configure KVM block-based live migration,
>> and it has the advantage of avoiding the need for shared storage of
>> instances.
>> 
>> However, there's this email from Daniel Berrangé from back in Aug 2012:
>> http://osdir.com/ml/openstack-cloud-computing/2012-08/msg00293.html
>> 
>> "Block migration is a part of the KVM that none of the upstream developers
>> really like, is not entirely reliable, and most distros typically do not
>> want to support it due to its poor design (eg not supported in RHEL).
>> 
>> It is quite likely that it will be removed in favour of an alternative
>> implementation. What that alternative impl will be, and when I will
>> arrive, I can't say right now."
>> 
>> Based on this info, the OpenStack Ops guide currently recommends against
>> using block-based live migration, but the Compute Admin guide has no
>> warnings about this.
>> 
>> I wanted to sanity-check against the mailing list to verify that this was
>> still the case. What's the state of block-based live migration with KVM?
>> Should we say be dissuading people from using it, or is it reasonable for
>> people to use it?
> 
> What I wrote above about the existing impl is still accurate. The new
> block migration code is now merged into libvirt and makes use of an
> NBD server built-in to the QMEU process todo block migration. API
> wise it should actually work in the same way as the existing deprecated
> block migration code.  So if you have new enough libvirt and new enough
> KVM, it probably ought to 'just work' with openstack without needing
> any code changes in nova. I have not actually tested this myself
> though.
> 
> So we can probably update the docs - but we'd want to checkout just
> what precise versions of libvirt + qemu are needed, and have someone
> check that it does in fact work.
> 
> Regards,
> Daniel
> -- 
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