Open Stack

On 03/11/2015 1:28 PM, "Robert Collins" <robertc at robertcollins.net> wrote:
>
> Hi, at the summit we had a big session on distributed lock managers
(DLMs).

Awesome.

>
> I'd just like to highlight the conclusions we came to in the session (
>     https://etherpad.openstack.org/p/mitaka-cross-project-dlm
>     )
>
> Firstly OpenStack projects that want to use a DLM can make it a hard
> dependency. Previously we've had a unwritten policy that DLMs should
> be optional, which has led to us writing poor DLM-like things backed
> by databases :(. So this is a huge and important step forward in our
> architecture.

Agreed and it's also a positive step.

>
> As in our existing pattern of usage for database and message-queues,
> we'll use an oslo abstraction layer: tooz. This doesn't preclude a
> different answer in special cases - but they should be considered
> special and exception, not the general case.
>
> Based on the project requirements surfaced in the discussion, it seems
> likely that all of konsul, etc and zookeeper will be able to have
> suitable production ready drivers written for tooz. Specifically no
> project required a fair locking implementation in the DLM.
>
> After our experience with oslo.messaging however, we wanted to avoid
> the situation of having unmaintained drivers and no signalling to
> users about them.
>
> So, we resolved to adopt roughly the oslo.messaging requirements for
> drivers, with a couple of tweaks...
>
> Production drivers in-tree will need:
>  - two nominated developers responsible for it
>  - gating functional tests that use dsvm
> Test drivers in-tree will need:
>  - clear identification that the driver is a test driver - in the
> module name at minimum
>
> All hail our new abstraction overlords.

This really is fantastic news.   Thanks for the 'heads up'.

Geoff

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