[openstack-dev] [TripleO] Move redis out of Pacemaker

Pradeep Kilambi prad at redhat.com
Mon Dec 12 15:29:45 UTC 2016

On Mon, Dec 12, 2016 at 8:58 AM, Giulio Fidente <gfidente at redhat.com> wrote:

> On 12/12/2016 02:51 PM, Giulio Fidente wrote:
>> On 12/09/2016 04:49 PM, Pradeep Kilambi wrote:
>>> Hey Folks:
>>> I would like to get some thoughts on $Subject. This came up when i was
>>> discussing the standalone roles for telemetry. Currently when we deploy
>>> redis in tripleo, its a pacemaker managed service. So if we were to
>>> deploy telemetry services on a dedicated node we could. But redis will
>>> have to be on a another node? (assuming we dont want to pull in
>>> pacemaker on to telemetry nodes).
>> currently redis instances are not configured as a redis cluster but use
>> the master/slave replication model instead and pacemaker is taking care
>> of electing/relocating the redis master as needed
>> there shouldn't be any dependency on the redis profile for the telemetry
>> roles, they should instead just point at the redis_vip
>> the redis_vip is always guaranteed (by haproxy) to point to the redis
>> master
>> With most services moved out of pacemaker in Newton, I think its time to
>>> move redis as well? Are there any constraints in moving redis to be
>>> managed by systemd? Looking at how we do it, It should be easily movable
>>> to systemd? Can we consider doing this for Ocata?
>> I think we could look at using the redis cluster which allows multiple
>> masters, but I am not sure this can happen in Ocata ... yet again, there
>> shouldn't be in the telemetry roles any dependency on redis itself
>> if we were to use the cluster mode the only difference would probably be
>> that the redis_vip will start balancing requests across the nodes
> also note that the cluster model is not replicating data across the nodes,
> but rather sharding the data, with the promise of surviving failures of
> some of the nodes and I'm not sure we want that anyway
> https://redis.io/topics/cluster-spec

 I just thought we could use redis sentinel to achieve the HA and avoid
pacemaker headache. Which i think is already integrated a while ago in
tripleo. Its just not used, As pacemaker is taking over the control.

See https://redis.io/topics/sentinel

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> Giulio Fidente
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