hi,
Von: Dejan Muhamedagic <deja...@fastmail.fm> An: The Pacemaker cluster resource manager <pacemaker@oss.clusterlabs.org> Datum: 28.10.2014 16:45 Betreff: Re: [Pacemaker] fencing with multiple node cluster > > >Hi, > >On Tue, Oct 28, 2014 at 09:51:02AM -0400, Digimer wrote: >>> On 28/10/14 05:59 AM, philipp.achmuel...@arz.at wrote: >>> hi, >>> >>> any recommendation/documentation for a reliable fencing implementation >>> on a multi-node cluster (4 or 6 nodes on 2 site). >>> i think of implementing multiple node-fencing devices for each host to >>> stonith remaining nodes on other site? >>> >>> thank you! >>> Philipp >> >> Multi-site clustering is very hard to do well because of fencing issues. >> How do you distinguish a site failure from severed links? > >Indeed. There's a booth server managing the tickets in >pacemaker, which uses arbitrators to resolve ties. booth source >is available at github.com and packaged for several >distributions at OBS >( http://download.opensuse.org/repositories/network:/ha-clustering:/Stable/) >It's also supported in the newly released SLE12. > >Thanks, > >Dejan > hi, @Digimer. thank you for explaination, but manual failover between sites isn't what i'm looking for. @Dejan. Yes, i already tried a cluster(SLES11SP3) with booth setup. i used documentation from sleha11 SP3. but i'm afraid it is unclear for me how "fencing" with booth exactly works in case of some failures (loss-policy=fence). documentation says something like: ...to speed up recovery process nodes get fenced... do i need classic node-fencing(IPMI) when i configure booth setup? may you have some more information about that? For correct setup, the arbitrator needs an adequate 3th location. site A and site B need separate connection to site C, otherwise some scenarios will fail. any possibilities to get this running with 2 sites? thank you! >> Given that a >> failed fence action can not be assumed to be a success, then the only >> safe option is to block until a human intervenes. This makes your >> cluster as reliable as your WAN between the sites, which is too say, not >> very reliable. In any case, the destruction of a site will require >> manual failover, which can be complicated if insufficient nodes remain >> to form quorum. >> >> Generally, I'd recommend to different clusters, one per site, with >> manual/service-level failover in the case of a disaster. >> >> In any case; A good fencing setup should have two fence methods. >> Personally, I always use IPMI as a primary fence method (routed through >> one switch) and a pair of switched PDUs as backup (via a backup switch). >> This way, when IPMI is available, a confirmed fence is 100% certain to >> be good. However, if the node is totally disabled/destroyed, IPMI will >> be lost and the cluster will switch to the switched PDUs, cutting the >> power outlets feeding the node. >> >> I've got a block diagram of how I do this: >> >> https://alteeve.ca/w/AN!Cluster_Tutorial_2#A_Map.21 >> >> It's trivial to scale the idea up to multiple node clusters. >> >> Cheers >> >> -- >> Digimer >> Papers and Projects: https://alteeve.ca/w/ >> What if the cure for cancer is trapped in the mind of a person without >> access to education? >> >> _______________________________________________ >> Pacemaker mailing list: Pacemaker@oss.clusterlabs.org >> http://oss.clusterlabs.org/mailman/listinfo/pacemaker >> >> Project Home: http://www.clusterlabs.org >> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf >> Bugs: http://bugs.clusterlabs.org > >_______________________________________________ >Pacemaker mailing list: Pacemaker@oss.clusterlabs.org >http://oss.clusterlabs.org/mailman/listinfo/pacemaker > >Project Home: http://www.clusterlabs.org >Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf >Bugs: http://bugs.clusterlabs.org
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