[Info-vax] Ksplice equivalent for VMS ?

[Arne Vajhøj]

On 2/19/2025 5:26 PM, Dan Cross wrote:
> In article <vp5dig$2dnk8$1 at dont-email.me>,
> Arne Vajhøj  <arne at vajhoej.dk> wrote:
>> I am thinking about a scenario like:
>> * cluster with node A and B
>> * critical process P that for whatever reason does not work
>>    running concurrent on multiple nodes runs on A
>> * node A needs to be taken down for some reason
>> * so VMS on node A and B does some magic and migrate P from A to B
>>    transparent to users (obviously require a cluster IP address or
>>    load balancer)
> 
> While this may be an acceptable method to "hotpatch" a host with
> minimal disruption to whatever workload it's running, it is
> completely unlike what ksplice does.  For one, it requires that
> sufficient resources exist in wherever you'd migrate the process
> to for the duration of the update.

That is a requirement.

:-)

>                                    Moreover, it requires that
> all aspects of state that are required to resume execution of
> the process are accessable and replicable on other, similar
> hardware.

Yes. Which becomes a little easier when restricted to a
cluster instead of any systems.

> Many hyperscalar cloud providers do something similar for
> updates, but there are serious limitations and downsides; for
> example, direct passthru to hardware devices (storage, compute
> accelerators, etc) can make it impossible to move a VM.

Moving VM's is common. Robert started by mentioning vMotion.

Arne