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.
This was an artifact of a much, much older Ceph configuration I ran, and
is not relevant with newer Ceph versions like those used in PVC.
Performance testing with Nautilus and Bluestore reveals a minimal
performance hit, and using `jemalloc` prevents cache autotuning from
being effective, so remove it.
Adds this option based on the findings of
https://github.com/python-zk/kazoo/issues/630, whereby restores of >1MB
in size would fail. This is considered an unsafe option, but given our
usecase no actual znode should ever exceed this limit; this is purely
for the large transactions that come from a `pvc task restore` action to
an empty Zookeeper instance.
This playbook will perform a oneshot upgrade of the systems in the
cluster, including performing a clean and safe reboot of the node(s) if
required (either due to services needing a restart, or the kernel
changing). It runs in serial=1 and only reboots if needed.
Joshua Boniface