[openstack-dev] [nova] Distributed locking

Joshua Harlow harlowja at yahoo-inc.com
Sat Jun 14 14:12:49 UTC 2014


Are the details of that implementation described on wiki or elsewhere? (Partially for my own curiosity). I think I understand how it works but write ups usually clear that right up.

Sent from my really tiny device...

> On Jun 14, 2014, at 12:15 AM, "Robert Collins" <robertc at robertcollins.net> wrote:
> 
>> On 13 June 2014 02:30, Matthew Booth <mbooth at redhat.com> wrote:
>> We have a need for a distributed lock in the VMware driver, which I
>> suspect isn't unique. Specifically it is possible for a VMware datastore
>> to be accessed via multiple nova nodes if it is shared between
>> clusters[1]. Unfortunately the vSphere API doesn't provide us with the
>> primitives to implement robust locking using the storage layer itself,
>> so we're looking elsewhere.
> 
> Perhaps I'm missing something, but I didn't see anything in your
> description about actually needing a *distributed* lock, just needing
> a local that can be held by remote systems. As Devananda says, a
> centralised lock that can be held by agents has been implemented in
> Ironic - such a thing is very simple and quite easy to reason about...
> but its not suitable for all problems. HA and consistency requirements
> for such a thing are delivered through e.g. galera in the DB layer.
> 
> -Rob
> 
> 
> -- 
> Robert Collins <rbtcollins at hp.com>
> Distinguished Technologist
> HP Converged Cloud
> 
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