On Wed, Sep 23, 2009 at 01:30:09AM +0300, Dan Frincu wrote: > bump > > anyone? > > Dan Frincu wrote: >> Hello all, >> >> I'm trying to build an architecture that I'm not 100% sure will work >> so I need some input on the matter. The design is: >> - 4 servers (now running on test xen virtual machines) >> - the servers will be divided in two separate geographical locations, >> 2 servers in site A and 2 servers in site B >> - each pair of servers from the same site will form a cluster >> - each cluster from both sites will be linked as a stacked resource >> (stacked-on-top-of) >> >> For this setup I'm using drbd-8.3.2-3.x86_64.rpm, >> heartbeat-3.0.0-33.2.x86_64.rpm, openais-0.80.5-15.1.x86_64.rpm, >> resource-agents-1.0-31.4.x86_64.rpm and their respective dependencies. >> >> One question that popped to my mind was that pacemaker is using >> multicast, so the connection between the two sites (if it is done >> through the public internet) should involve multicast routing? What >> bandwidth requirements should be for this kind of setup? I'm assuming >> that the high end requirements will be on the drbd replication part, >> but also I'm interested if there are any specific requirements related >> to latency, delay and (probably) jitter on the multicast connection as >> it uses (correct me if I'm wrong) UDP as a transport?
You could use pacemaker + heartbeat cluster comm. or you could just do independent clusters, and have an admin intervene and switch on side "global target role attribute" to started or some such, I don't think you really want to fully automate site failover just yet. >> So far I've configured all 4 virtual machines with drbd, created >> "normal" resources, stacked resources and all seems to be in order, >> the problem is that I don't know how does pacemaker deal with stacked >> resources. There should be a section in the DRBD users guide by now, check it out. Basically you just configure two ocf:linbit:drbd thingies, and have one depend on the Master role of the other. >> I mean, the goal here is to have one service, let's say apache, run on >> a device on the stacked resource and to be handled by pacemaker so >> that the apache server either runs on primary stacked resource on site >> A, or fails over on stacked resource on site B, and underneath all >> that, if in site A one of the two servers fails, it switches to the >> other one and the same should happen in site B. I'm not sure about the split-site cluster with fully automated site-failover. I'd go for the "operator interaction required", half-automated site-failover case, in which case you do not really need all four nodes in the same pacemaker cluster anyways. >> So the question is, how do I get pacemaker to start both normal and >> stacked resources, promote normal and stacked resources as primary and >> then start a web server on the stacked resource that becomes primary. proper constraints ;) Apache -> Filesystem -> drbd-top:Master -> drbd-lower:Master >> Any relevant documentation links or examples are more than welcome, >> as well as ideas and suggestions. -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. _______________________________________________ Pacemaker mailing list Pacemaker@oss.clusterlabs.org http://oss.clusterlabs.org/mailman/listinfo/pacemaker