Hello,

Just to add some context here. We plan to use slurm for developing a sched solution which interacts with a backend system.

Now, the backend system has pieces of h/w which require specific host in the allocation to be the primary/master host wherein the initial task would be launched, this in turn is driven by the job's placement orientation on the h/w itself.

So, our primary task should launch in the asked primary host while secondary / remote tasks would subsequently get started on other hosts.

Hope this brings some context to the problem as to why a specific host is necessary to be the starting host.

Regards,
Bhaskar.

On Thursday 31 October, 2024 at 12:04:37 am IST, Laura Hild <lsh@jlab.org> wrote:


I think if you tell the list why you care which of the Nodes is BatchHost, they may be able to provide you with a better solution.


________________________________________

Od: Bhaskar Chakraborty via slurm-users <slurm-users@lists.schedmd.com>
Poslano: sreda, 30. oktober 2024 12:35
Za: slurm-users@schedmd.com
Zadeva: [slurm-users] Change primary alloc node

Hi,

Is there a way to change/control the primary node (i.e. where the initial task starts) as part of a job's allocation.

For eg, if a job requires 6 CPUs & its allocation is distributed over 3 hosts h1, h2 & h3 I find that it always starts the task in 1 particular
node (say h1) irrespective of how many slots were available in the hosts.

Can we somehow let slurm have the primary node as h2?

Is there any C-API inside select plugin which can do this trick if we were to control it through the configured select plugin?

Thanks.
-Bhaskar.