Would it make sense to require ntp

[Nathan Cutler <ncutler@suse.cz>]

Hi Ceph:

Recently I encountered some a "clock skew" issue with 0.94.3. I have
some small demo clusters in AWS. When I boot them up, in most cases the
cluster will start in HEALTH_WARN due to clock skew on some of the MONs.

I surmise that this is due to a race condition between the ceph-mon and
ntpd systemd services. Sometimes ntpd.service starts *after* ceph-mon -
in this case the MON sees a wrong/unsynchronized time value.

Now, even though ntpd.service starts (and fixes the time value) very
soon afterwards, the cluster remains in clock skew for a long time - but
that is a separate issue. What I would like to ask is this:

Is there any reasonable Ceph cluster node configuration that does not
include running the NTP daemon?

If the answer is "no", would it make sense to make NTP a runtime
dependency and tell the ceph-mon systemd service to wait for
ntpd.service before it starts?

Thanks and regards

-- 
Nathan Cutler
Software Engineer Distributed Storage
SUSE LINUX, s.r.o.
Tel.: +420 284 084 037