Thanks Joao for information. Many Thanks Karan Singh ----- Original Message ----- From: "Joao Eduardo Luis" <joao.luis@xxxxxxxxxxx> To: ceph-users@xxxxxxxxxxxxxx Sent: Tuesday, 17 December, 2013 2:56:23 PM Subject: Re: After reboot nothing worked On 12/17/2013 09:54 AM, Karan Singh wrote: > Umar > > *Ceph is stable for production* , there are a large number of ceph > clusters deployed and running smoothly in PRODUCTIONS and countless in > testing / pre-production. > > Since you are facing problems with your ceph testing , it does not mean > CEPH is unstable. > > I would suggest put some time troubleshooting your problem. > > What i see from your logs -- > > 1) you have 2 Mons thats a problem ( either have 1 or have 3 to form > quorum ) . Add 1 more monitor node Just to clarify this point a bit, one doesn't need an odd number of monitors in a ceph cluster to reach quorum. This is a common misconception. The requirement to reach quorum is simply to have a majority of monitors able to talk to each other. If one has 2 monitors and both are able to talk to each other they'll be able to form a quorum. Odd-numbers are advised however because one can tolerate as much failures with less infrastructure. E.g., - for n = 1, failure of 1 monitor means loss of quorum - for n = 2, failure of 1 monitor means loss of quorum - for n = 3, failure of 1 monitor is okay; failure of 2 monitors means loss of quorum - for n = 4, failure of 1 monitor is okay; failure of 2 monitors means loss of quorum - for n = 5, failure of 2 monitors is okay; failure of 3 monitors means loss of quorum - for n = 6, failure of 2 monitors is okay; failure of 3 monitors means loss of quorum etc. So you can see how you don't get any benefits, from an availability perspective, by having either 2, 4 or 6 monitors when compared to having 1, 3, 5. If your target however is replication, then 2 is better than 1. -Joao -- Joao Eduardo Luis Software Engineer | http://inktank.com | http://ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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