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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
-- 
Giulio Fidente
GPG KEY: 08D733BA