There are configurations and sequences of events that can lead to forests remaining online when there are N/2 or fewer hosts online.
In the simplest case, if you have a forest that is not configured for either local or shared disk failover, as long as the forest's host is up the forest will be available regardless of any quorum issues. In this case, as long as a database's forests are available, the database will be available. For local disk failover, forests that are "sync replicating" will transition to "open" in response to a host failure that makes the "open" forest inaccessible, but an "open" forest will not go offline in response to some other host failing. However, once you lose quorum, no forests will failover anymore if you lose another host. Given that, and depending on how your forests are distributed and the order of host failures, it's possible that you can remain online even though enough hosts have failed that you no longer have quorum. You just can't rely on staying online with that many failed hosts. Databases with many forests spread across many hosts typically can't stay online if you lose quorum because some forest(s) will become unavailable. What sort of failover do you have configured? Wayne. On 12/19/2014 08:00 AM, Whitby, Rob wrote: > thanks Danny, > > so what triggers the voting? Not having all the forests available? > > > > From: Danny Sinang <[email protected] <mailto:[email protected]>> > Reply-To: MarkLogic Developer Discussion > <[email protected] <mailto:[email protected]>> > Date: Friday, 19 December 2014 15:44 > To: MarkLogic Developer Discussion <[email protected] > <mailto:[email protected]>> > Subject: Re: [MarkLogic Dev General] cluster quorum > > The downed hosts probably did not contain the master forests, so no > quorum vote was called for. > > We have the same setup. We can even go to just having one host alive > and still serve data. > > Regards, > Danny > > Sent from my iPhone > > On Dec 19, 2014, at 10:39 AM, Whitby, Rob <[email protected] > <mailto:[email protected]>> wrote: > >> Hi, >> >> I have a cluster with 6 hosts. I stopped 3 of the hosts and the >> remaining 3 are still accepting reads/writes. >> >> Why is this? I was expecting the quorum not to be reached because we >> don’t have >50% of hosts available. >> >> https://help.marklogic.com/knowledgebase/article/View/119/0/start-up-quorum-and-forest-level-failover >> >> Cheers >> Rob >> >> _______________________________________________ >> General mailing list >> [email protected] <mailto:[email protected]> >> http://developer.marklogic.com/mailman/listinfo/general > > > _______________________________________________ > General mailing list > [email protected] > http://developer.marklogic.com/mailman/listinfo/general -- Wayne Feick Principal Engineer MarkLogic Corporation [email protected] Phone: +1 650 655 2378 www.marklogic.com This e-mail and any accompanying attachments are confidential. The information is intended solely for the use of the individual to whom it is addressed. Any review, disclosure, copying, distribution, or use of this e-mail communication by others is strictly prohibited. If you are not the intended recipient, please notify us immediately by returning this message to the sender and delete all copies. Thank you for your cooperation.
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