[Info-vax] Ksplice equivalent for VMS ?

[Stephen Hoffman]

On 2025-02-19 19:50:53 +0000, Robert A. Brooks said:

> On 2/19/2025 14:10, Arne Vajhøj wrote:
>> On 2/19/2025 10:05 AM, Robert A. Brooks wrote:
>>> On 2/19/2025 08:25, Simon Clubley wrote:
>>>> Oracle have a kernel patching tool called Ksplice that they acquired
>>>> back in 2011. It allows their support contract Linux users to apply
>>>> many Linux kernel patches without having to reboot the server:
>>>> 
>>>> https://en.wikipedia.org/wiki/Ksplice
>>>> 
>>>> Given the high-availability mindset for VMS users, I wonder if VSI ever
>>>> considered creating something similar for VMS ?
>>> 
>>> No.

DEC OpenVMS Engineering did look at work akin to Ksplice (with some 
predecessor dynamic-patch tool), but that was a very long time ago. It 
was not particularly feasible within what was then available, and the 
task has probably only gotten more difficult.

Getting consistent online backups was another related discussion around 
the same era, but that proposal never became a project.

IIRC, there were patching-related patents from HP, Microsoft, and other 
organizations starting in the early 2000s, though some of those patents 
took an appeal or two and a few years to be granted.

Some related and more recent reading: 
https://web.eecs.umich.edu/~weimerw/p/weimer-dsn2020-kshot.pdf

The provided alternative within OpenVMS is a rolling reboot in a 
cluster, with cluster-aware apps. That's documented and supported, and 
works well. Works within Galaxy configurations, too.

There's not much documentation on creating cluster-aware apps 
unfortunately, and the necessary APIs are scattered around the docs, 
but various developers have succeeded in that task. I've written a few 
of these cluster-aware apps over the years too, though the cluster 
pricing scared many if not most sites away from that approach.

Another option here is Erlang, as well.

Quiescing apps and triggering some shadowing shenanigans was an option 
for obtaining consistent backups, though lots of apps "borrowed" a 
database with journaling support. Some few apps use RMS journaling too, 
but that feature never caught on widely.

>> What about process migration?
> 
> Like Galaxy on Alpha?

OpenVMS Galaxy can't migrate processes across instances, though. 
Processors, yes. Processes, no.

Semi-related, DEC had Checkpoint-Restart AKA Snapshot AKA FastBoot on 
standalone VAX workstations, and had support for that starting at 
OpenVMS VAX V6.0, and support for that was withdrawn at OpenVMS VAX 
V7.1.

> There is vMotion for virtual machines on ESXi, but that's not exactly the same.

You're most definitely right about that. It's not the same.

I'd not expect to see anything approaching KSplice for OpenVMS from VSI.


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