On Thu, Dec 07, 2017 at 09:59:43AM +0100, Marcus Priesch wrote: > Hello Brad, > > thanks for your answer ! > > >> at least the point of all is that a single host should be allowed to > >> fail and the vm's continue running ... ;) > > > > You don't really have six MONs do you (although I know the answer to > > this question)? I think you need to take another look at some of the > > docs about monitors. > > however i dont get the point here ... > > because its an even number ? > > i read docs ... but dont get any hints on the number of mons ... i would > assume, the more the better ... is this wrong ?
an even number is always bad for quorum based systems (6 is no better than 5, as you can only tolerate a loss of 2 before losing quorum). in Ceph, additional monitors require additional resources AND generate additional overhead (more mons -> more communication). the rule of thumb is 3 for small to mid-sized cluster. the next step up performance wise would be to move the 3 mons to their own stand-alone nodes, and only once that starts to bottleneck, you increase the number to 5 and/or upgrade the HW to become faster. for really big clusters, you can then start splitting out the mgr instances to reduce the load further. _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
