[Info-vax] Wide area cluster, metro area network, seeking info

[Mark Berryman]

On 6/14/21 1:56 PM, Michael Moroney wrote:
> On 6/14/2021 12:44 AM, Phillip Helbig (undress to reply) wrote:
>> In article <sa6ge0$sra$1 at dont-email.me>, Mark Berryman
>> <mark at theberrymans.com> writes:
>>
>>> On 6/12/21 1:01 AM, Phillip Helbig (undress to reply) wrote:
>>>> In article <sa11hi$cpc$1 at dont-email.me>, Mark Berryman
>>>> <mark at theberrymans.com> writes:
>>>>
>>>>> First, I recommend you ignore the suggestions to add a 3rd node to 
>>>>> your
>>>>> cluster.  In your situation, it is not really a viable answer.
>>>>
>>>> It would solve most of the problems you mention below, and also could
>>>> serve as a test node.
>>>>
>>>>> There are configurations that will allow a member of a 2-node 
>>>>> cluster to
>>>>> automatically continue in the event that the other node fails.
>>>>
>>>> How?  If one has more votes, it is essential.  If the votes are the
>>>> same, both are essential.  Unless you mean a quorum disk.  But it 
>>>> should
>>>> be at a third location.
>>>>
>>>
>>> Situation: two separate nodes with no shared storage
>>>
>>> Configure each node with one vote.  Configure each node to use a local
>>> disk as the quorum disk, also with one vote.
>>>
>>> As the cluster is formed, the nodes will discover that they do not agree
>>> on the quorum disk and will exclude it, resulting in quorum being
>>> established with the 2 votes provided by the nodes.
>>>
>>> One node goes down, the other pauses while it recomputes quorum.  In
>>> doing so it discovers there is no longer a conflict regarding the quorum
>>> disk so it includes it, resulting in two votes which re-achieves quorum
>>> and the node continues.
>>>
>>> When the failed node comes back up, the quorum disks will be excluded
>>> again and the cluster will return to its original state.  The danger of
>>> this configuration is that, if the communication channel between the two
>>> nodes is lost but the nodes remain up, the cluster will partition.  This
>>> is addressed in my original posting.
>>
>> Is this scenario supported?
>>
> No!

According to whom?

It was certainly supported by Digital when they gave me the set up back 
in the 80s.

Mark Berryman