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

[Arne Vajhøj]

On 1/4/2021 1:17 PM, Simon Clubley wrote:
> On 2021-01-04, Arne Vajhøj <arne at vajhoej.dk> wrote:
>> 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.
> 
> That's what I thought but I wasn't 100% sure just in case something had
> come along without me hearing about it.
> 
>> But application failover is a pretty universal feature also outside
>> of VMS, Implementation techniques vary a lot.
> 
> So it's the same as always in that you also need the additional supporting
> infrastructure to provide what you get as standard with VMS clustering,

Not really.

It is a typical feature of the software you are running.

Your database, application server, web server, cache
server or whatever server cluster provides it.

Arne