[openstack-dev] [cinder] [nova] locking concern with os-brick

Sean McGinnis sean.mcginnis at gmx.com
Fri Aug 12 13:24:03 UTC 2016

On Fri, Aug 12, 2016 at 05:55:47AM -0400, Sean Dague wrote:
> A devstack patch was pushed earlier this cycle around os-brick -
> https://review.openstack.org/341744
> Apparently there are some os-brick operations that are only safe if the
> nova and cinder lock paths are set to be the same thing. Though that
> hasn't yet hit release notes or other documentation yet that I can see.

Patrick East submitted a patch to add a release note on the Cinder side
last night: https://review.openstack.org/#/c/354501/

> Is this a thing that everyone is aware of at this point? Are project
> teams ok with this new requirement? Given that lock_path has no default,
> this means we're potentially shipping corruption by default to users.
> The other way forward would be to revisit that lock_path by default
> concern, and have a global default. Or have some way that users are
> warned if we think they aren't in a compliant state.

This is a very good point that we are shipping corruption by default. I
would actually be in favor of having a global default. Other than
requiring tooz for default global locking (with a lot of extra overhead
for small deployments), I don't see a better way of making sure the
defaults are safe for those not aware of the issue.

And IMO, having the release note is just a CYA step. We can hope someone
reads it - and understands it's implications - but it likely will be

Anyway, that's my 2 cents.


> I've put the devstack patch on a -2 hold until we get ACK from both Nova
> and Cinder teams that everyone's cool with this.
> 	-Sean
> -- 
> Sean Dague
> http://dague.net
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