Thanks Greg, Joao and David, The concept why odd no. of monitors are preferred is clear to me, but still I am not clear about the working of Paxos algorithm: #1. All changes in any data structure of monitor whether it is monitor map, OSD map, PG map, MDS map or CRUSH map; are made through Paxos algorithm and #2. Paxos algorithm also establish a quorum among the monitors for recent copy of cluster map. I am unable to understand how these two things are related and connected ? how does Paxos provide these two functionalities? Please help to clarify these points. Regards Pragya Jain On Saturday, 30 August 2014 7:29 AM, Joao Eduardo Luis <joao.luis at inktank.com> wrote: > > >On 08/29/2014 11:22 PM, J David wrote: > >> So an even number N of monitors doesn't give you any better fault >> resilience than N-1 monitors. And the more monitors you have, the >> more traffic there is between them. So when N is even, N monitors >> consume more resources and provide no extra benefit compared to N-1 >> monitors. > >Except for more copies ;) > >But yeah, if you're going with 2 or 4, you'll be better off with 3 or 5. > As long as you don't go with 1 you should be okay. Only go with 1 if >you're truly okay with losing whatever you're storing if that one >monitor's disk is fried. > > -Joao > > >-- >Joao Eduardo Luis >Software Engineer | http://inktank.com | http://ceph.com > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140830/4536b44d/attachment.htm>
 |