Due to the requirement of Ceph to have all peer nodes tightly
synchronized with each other to come online, PVC nodes need a way to
synchronize to each other even in the absence of an external time
reference. This is especially prevalent if a set of nodes are left
offline for an extended period (>1-2 weeks), since their hardware clocks
will drift. If the resulting Internet connectivity is then dependent on
a VM, this will cause a catch-22 and the cluster will not properly
start.
This configuration will accomplish that - if no suitable >6 stratum
peers are found, the hosts will enter orphan mode. Since they are now
all configured as "peers" with each other, they will collectively decide
on one of them to become the source and sync to it. A local stratum 10
fudge is added so that at least one of the nodes can become this source.
While this is not an ideal use of NTP, it is by far the cleanest
solution to this problem, and does not impact normal functionality when
the two configured stratum-2 servers are reachable.
Joshua Boniface