Hi Pradeep, On Mon, Dec 12, 2016 at 02:51:59PM +0100, Giulio Fidente wrote: > On 12/09/2016 04:49 PM, Pradeep Kilambi wrote: > >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).
Ok so with the composable HA work [1] you should be able to split out the redis service on to dedicated nodes and these nodes can be either full pacemaker cluster members or only have the pacemaker-remote service. > 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 In general I am in favour to split out redis from pacemaker. There is the question that in theory we'd have two potentially separate quorums, but I think that with redis this should not be a big problem. Maybe let's start with a prototype and see how things look and iterate from there? I think it is a bit late for ocata, but we could at least start the work without changing the defaults (i.e. let the operator override the tripleo::service with a redis base profile instead of the pacemaker one) Does that make sense, Michele [1] https://review.openstack.org/#/q/topic:bp/composable-ha -- Michele Baldessari <mich...@acksyn.org> C2A5 9DA3 9961 4FFB E01B D0BC DDD4 DCCB 7515 5C6D __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev