[openstack-dev] [nova] Distributed locking

Robert Collins robertc at robertcollins.net
Sat Jun 14 07:11:43 UTC 2014

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.


Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud

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