thnx Jens
> > I have my testcluster consisting two OSDs that also host MONs plus
> > one to five MONs.
> Are you saying that you have a total of 7 mons?
yepp
> > down the at last, not the other MON though (since - surprise - they
> > are in this test szenario just virtual instances residing on some
> > ceph rbds)
> This seems to be your problem. When you shutdown the cluster, you
> haven't got those extra mons.
>
> In order to reach a quorum after reboot, you need to have more than half
> of yours mons running.
wait!
lets say in my setup (which might be silly giving the MON / OSD ratio but
still)with 7 MONs I have to have at least 5 MONS running?4 would be more than
the half but insufficient to reach a quorum.But, would the cluster come up at
all if I could get only 3 out of the 7 initial MONs up and running?
> If you have 5 or more mons in total, this means that the two physical
> servers running mons cannot reach quorum by themselves.
>
> I.e. you have 2 mons out of 5 running for example - it will not reach a
> quorum because you need at least 3 mons to do that.
Well, as I said, I had 3 MONs running, just the sequence in which they came up
after the reboot was odd,first the first MON/OSD combination came to life, than
a second MON, than the second MON/OSD combination
> You need to either move mons to physical machines, or virtual instances
> not depending on the same Ceph cluster, or reduce the number of mons in
> the system to 3 (or 1).
And do I need to make sure that a quorum capable number of MONs is up BEFORE I
restart the OSDs?
than the sequence would be:
- free cluster of load/usage
- stop MDS / any given order
- stop OSD / any given order
- stop MON / one after the other
- start MON / in reverse order, last shutdown is first boot
- start OSD
- start MDS
- allow load to the cluster again
central question remains, do I need 5 out of 7 MONs running or would 3 out of 7
be sufficient?
TIA
Bernhard
--
Bernhard Glomm
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