Sergio, Some customers have a previously optimized etcd cluster(s). We can have OpenShift point at that cluster, if so desired. That is the External Etcd scenario. This can reduce significant load from the Master nodes. The other scenario is when OpenShift installs an etcd cluster on the Master nodes. I rarely hear about the former scenario anymore.
As for Masters, the idea is that etcd quorum [0] (in the latter scenario above) is optimally achieved when we have `(n+1)/2` agreement. Essentially, what that means that we start with 3 members (2 needed to achieve quorum) and we should increase the cluster by 2 members to continue along that curve. However, since etcd needs to sync it's DB across the Masters, we great greatly increase our network traffic requirements needed for syncing the DB between the masters for relatively little availability gain. [0] https://coreos.com/etcd/docs/latest/faq.html ___________________________________________________ LOUIS P. SANTILLAN Architect, OPENSHIFT & DEVOPS Red Hat Consulting, <https://www.redhat.com/> Container and PaaS Practice [email protected] M: 3236334854 <https://red.ht/sig> TRIED. TESTED. TRUSTED. <https://redhat.com/trusted> On Wed, Feb 27, 2019 at 4:55 AM Sérgio Cascão <[email protected]> wrote: > hi Trevor, thanks for your response. > > in your link they talk about HA, and these case you have one etcd for > each master, if the one master goes down, you have always the etcd > available. > > >> It therefore provides an HA setup where losing a control plane instance >> or an etcd member has less impact and does not affect the cluster >> redundancy as much as the stacked HA topology. > > > But my question is more about performance, for example, i know that > inplementation you have more latency in acess to master. if you can show me > more vantages and advantages I would be grateful. > > best regards > Sergio > > W. Trevor King <[email protected]> escreveu no dia terça, 26/02/2019 à(s) > 22:30: > >> On Tue, Feb 26, 2019 at 2:26 PM Sérgio Cascão wrote: >> > i like know what the advantages between put etcd separated from masters? >> >> Some more docs around these choices in [1]. >> >> Cheers, >> Trevor >> >> [1]: https://kubernetes.io/docs/setup/independent/ha-topology/ >> > _______________________________________________ > users mailing list > [email protected] > http://lists.openshift.redhat.com/openshiftmm/listinfo/users >
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