What is the mystery? Two is not more than half of four. Therefore, two machines is not a quorum for a four machine Zookeeper ensemble.
wunder On Dec 6, 2012, at 4:50 PM, Jack Krupansky wrote: > It's still an unresolved mystery, for now. > > -- Jack Krupansky > > -----Original Message----- From: Walter Underwood > Sent: Thursday, December 06, 2012 7:30 PM > To: solr-user@lucene.apache.org > Subject: Re: Minimum HA Setup with SolrCloud > > The Zookeeper ensemble knows the total size. It does not adjust it each time > that a machine is partitioned or down. > > Two machines is not a quorum for a four machine ensemble. > > Why do you think that the documentation would get this wrong? > > wunder > > On Dec 6, 2012, at 4:14 PM, Jack Krupansky wrote: > >> But that is the context I was originally referring to - that with 4 zk you >> can lose only one, that you can't lose two. So, if you want to tolerate a >> loss on one, 4 zk would be the minimum... but then it was claimed that you >> COULD start with 3 zk and loss of one would be fine. I mean whether you >> start with 4 and lose 2 or start with 3 and lose 1 is the same, right? >> >> -- Jack Krupansky >> >> -----Original Message----- From: Yonik Seeley >> Sent: Thursday, December 06, 2012 6:34 PM >> To: solr-user@lucene.apache.org >> Subject: Re: Minimum HA Setup with SolrCloud >> >> On Thu, Dec 6, 2012 at 5:55 PM, Jack Krupansky <j...@basetechnology.com> >> wrote: >>> I trust that you have the right answer, Mark, but maybe I'm just struggling >>> to parse this statement: "the remaining two machines do not constitute a >>> majority." >>> >>> If you start with 3 zk and lose one, you have an ensemble that does not >>> "constitute a majority". >> >> I think you took that out of context. They were talking about losing >> 2 nodes in a 4 node cluster. >> >> "For example, with four machines ZooKeeper can only handle the failure >> of a single machine; if two machines fail, the remaining two machines >> do not constitute a majority." >> >> -Yonik >> http://lucidworks.com > > -- > Walter Underwood > wun...@wunderwood.org > > > -- Walter Underwood wun...@wunderwood.org
