On Thu, Jul 14, 2011 at 7:11 AM, RNZ <renoi...@gmail.com> wrote: > > > On Thu, Jul 14, 2011 at 4:46 PM, Serge Dubrouski <serge...@gmail.com>wrote: > >> >> >> On Thu, Jul 14, 2011 at 5:28 AM, Florian Haas <florian.h...@linbit.com>wrote: >> >>> On 2011-07-14 12:55, RNZ wrote: >>> > >>> > >>> > On Thu, Jul 14, 2011 at 2:02 PM, Florian Haas <florian.h...@linbit.com >>> > <mailto:florian.h...@linbit.com>> wrote: >>> > >>> > On 2011-07-14 08:46, RNZ wrote: >>> > > No, I want and I need - multi-master scheme (more then two >>> nodes)... >>> > >>> > There is nothing in Pacemaker's master/slave scheme that restricts >>> you >>> > to a single master. The ocf:linbit:drbd resource agent, for >>> example, is >>> > configurable in dual-Master mode. >>> > >>> > Once the resource agent properly implements the functionality (the >>> hard >>> > part), configuring a multi-master master/slave set is simply a >>> question >>> > of setting the master-max meta parameter to a value greater than 1 >>> (the >>> > easy part). >>> > >>> > I don't think so... Couchdb RESTful API very easy allow running >>> > repliacate by next scheme: >>> >>> It's entirely possible that the couchdb native API may be more powerful >>> in specific regards, but if you want to put it into a Pacemaker cluster >>> you may have to occasionally accept some minor limitations. That's a >>> tradeoff which is present for all Pacemaker managed applications. >>> >>> > primitive cdb0 >>> > hostA: hostB:dbB > localhost:dbB >>> > hostA: hostC:dbC > localhost:dbC >>> > hostA: hostD:dbD > localhost:dbD >>> > primitive cdb1 >>> > hostB: hostA:dbB > localhost:dbB >>> > primitive cdb2 >>> > hostC: hostA:dbC > localhost:dbC >>> > >>> > In this scheme hostA used as master for hostB and hostC (master-master) >>> > and as slave for hostD (slave-master). Both (master-master and >>> > slave-master for different servers/databases) scheme per one instance. >>> >>> So you mean there would be a cascading replication, like so: >>> >>> hostD >>> | >>> hostA >>> / \ >>> hostB hostC >>> >>> Such a thing is not something Pacemaker caters for specifically, but I >>> dare say it doesn't need to, either. You would simply create one >>> master/slave set where D is master and A is slave, and another where A >>> is master and B and C are slaves. >>> >> >> Wouldn't such configuration mean running 2 instances of a resource on >> nodeA? I doubt that that would be a right solution. >> > > No. Example present at end of file RA > https://github.com/rnz/resource-agents/blob/master/heartbeat/couchdb >
Sorry, it was a question to Florian about his vision how to implemented cascading replication in the Pacemaker master/slave model. Cascading replication can exist in OpenLDAP for example and there one node can be a slave to another and yet be a master for the third one. I currently do no see how that can be described in Pacemaker configuration even if OpenLDAP master/slave RA existed. > _______________________________________________________ > Linux-HA-Dev: Linux-HA-Dev@lists.linux-ha.org > http://lists.linux-ha.org/mailman/listinfo/linux-ha-dev > Home Page: http://linux-ha.org/ > > -- Serge Dubrouski.
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