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

[Phillip Helbig undress to reply]

In article <sa0jlu$9hn$1 at dont-email.me>, Stephen Hoffman
<seaohveh at hoffmanlabs.invalid> writes: 

> On 2021-06-11 20:35:24 +0000, Phillip Helbig (undress to reply said:
> 
> > A two-node cluster either has each node with equal votes...
> > 
> > Unless the office is at one of the locations, just put a third 
> > node---the smallest you can find---in the office...
> 
> There's little reason to run a one and one vote two-host configuration, 

Right.

> nor particular reason to license a third cluster node co-resident with 
> either lobe unless there's also shared storage involved within that 
> lobe.

Note that I said in the office, not co-resident with any of the main 
nodes.  Yes, a license will cost something.  On the other hand, one has 
a node which is a full cluster member yet not responsible for the main 
production stuff, so one can test things like reboots, backups, and so 
on, which one can't do with a quorum disk.

> The former as a failure in either lobe stalls all, the latter as it's 
> little different from a one and none voting configuration and it costs 
> way more.

The minimum is three nodes (or two nodes and a quorum disk, but see 
above), but in three separate locations.

> Same for using a quorum disk in any cluster without also having a 
> shared interconnect; assign those no-shared-interconnect quorum disk 
> votes to the host.

A quorum disk makes little sense without a shared interconnect.