[Info-vax] WHY IS VSI REQUIRING A HYPERVISOR FOR X86 OPENVMS?

[Arne Vajhøj]

On 1/4/2021 8:23 AM, Simon Clubley wrote:
> On 2021-01-01, Jan-Erik Söderholm <jan-erik.soderholm at telia.com> wrote:
>> With SAN, you can have HBS between datacenters without running VMS-Cluster.
>> Just shadow multiple disks from different SAN systems at different sites.
>> Or let the SAN systems hande the mirrowing of your data.
> 
> That takes care of the data.
> 
> What about the coordination between application and operating system
> instances at different sites so that another one picks up the load after
> the original instance fails ?
> 
> How is the original instance blocked from resuming operations if it
> recovers so that you don't have two instances of the application or
> operating system trying to update the same data at the same time in
> an uncoordinated way ?
> 
> In other words, what is the SAN version of the DLM and the VMS clustering
> protocols ?

That is not the job of the SAN.

But application failover is a pretty universal feature also outside
of VMS, Implementation techniques vary a lot.

Arne