[Info-vax] free shell accounts?

[David Froble]

Stan Radford wrote:
> On 2015-01-20, Matthew H McKenzie <news.deleteme at swellhunter.org> wrote:
>> No issues so far, but it is not a cluster, Deathrow could lose a node and 
>> still be usable. Of course recompilation was necessary across architectures 
>> and not everything is 100% portable. They have a log of incidents if you 
>> wish to look at recent history.
> 
> I don't understand what a cluster does. If they don't have shared disks
> somewhere wouldn't they have to have multiple copies of everything? How does
> a cluster still remain usable if you are editing a file and the machine the
> file lives on fails? I can see for serving applications a cluster would be
> great but I don't understand how it helps development users. And even that
> would seem like it would take a lot of planning and wouldn't just automatically
> "work" because of the need for shared storage somewhere.
> 
>> Should be OK for generic DCL, COBOL, C etc.  on a "best effort basis". 
>> Better than emulation at least.
> 
> Thanks.
> 
> Stan

The concept of a VMS cluster is "shared everything".  There can be 
various implementations.

For best versitility, each computer (node) would have a connection to 
every device.  Thus, if a particular node in the cluster goes down, all 
other nodes still have access to all devices.

Now, it is also possible for devices to be connected to a single node, 
and that node can share them with the cluster, but such devices are lost 
to the cluster if that node goes down.

With today's technology, some people use SANs, and then each node in the 
cluster is basically a "compute device".  As long as one node and the 
SAN is up, the cluster exists.

I may not be the best source of cluster information, and I'm pretty sure 
that except for an brief overall description a newsgroup post is not the 
best place to learn about cluster details.