[ClusterLabs] questions about startup fencing

[Adam Spiers]

Klaus Wenninger <kwenning at redhat.com> wrote:
>On 11/29/2017 04:23 PM, Kristoffer Grönlund wrote:
>> Adam Spiers <aspiers at suse.com> writes:
>>
>>> - The whole cluster is shut down cleanly.
>>>
>>> - The whole cluster is then started up again.  (Side question: what
>>>   happens if the last node to shut down is not the first to start up?
>>>   How will the cluster ensure it has the most recent version of the
>>>   CIB?  Without that, how would it know whether the last man standing
>>>   was shut down cleanly or not?)
>> This is my opinion, I don't really know what the "official" pacemaker
>> stance is: There is no such thing as shutting down a cluster cleanly. A
>> cluster is a process stretching over multiple nodes - if they all shut
>> down, the process is gone. When you start up again, you effectively have
>> a completely new cluster.
>>
>> When starting up, how is the cluster, at any point, to know if the
>> cluster it has knowledge of is the "latest" cluster? The next node could
>> have a newer version of the CIB which adds yet more nodes to the
>> cluster.
>
>To make it even clearer imagine a node being reverted
>to a previous state by recovering it from a backup.

Yes, I'm asking how this kind of scenario is dealt with :-)

Another example is a config change being made after one or more of the
cluster nodes had already been shut down.