On Mon, Mar 30, 2015 at 8:02 PM, Lindsay Mathieson <lindsay.mathie...@gmail.com> wrote: > On Tue, 31 Mar 2015 02:42:27 AM Kai KH Huang wrote: >> Hi, all >> I have a two-node Ceph cluster, and both are monitor and osd. When >> they're both up, osd are all up and in, everything is fine... almost: > > > > Two things. > > 1 - You *really* need a min of three monitors. Ceph cannot form a quorum with > just two monitors and you run a risk of split brain.
You can form quorums with an even number of monitors, and Ceph does so — there's no risk of split brain. The problem with 2 monitors is that a quorum is always 2 — which is exactly what you're seeing right now. You can't run with only one monitor up (assuming you have a non-zero number of them). > 2 - You also probably have a min size of two set (the default). This means > that you need a minimum of two copies of each data object for writes to work. > So with just two nodes, if one goes down you can't write to the other. Also this. > > > So: > - Install a extra monitor node - it doesn't have to be powerful, we just use a > Intel Celeron NUC for that. > > - reduce your minimum size to 1 (One). Yep. -Greg _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
