When this structure is fed to a EDR/HDR/FDR Infiniband network, the result is a blazing fast storage system where you can make a massive number of random accesses by very large number of servers simultaneously. The whole structure won't shiver even.
There are also other tricks Lustre can pull for smaller files to accelerate the access and reduce the overhead even further, too.
In this model, the storage boxes are somewhat sandboxed, but the whole model as a general is mounted via its own client, so the OS is very close to the model Lustre provides.
On the GPU servers, if you're going to provide big NVMe scratch spaces (a-la nVidia DGX systems), you soft-RAID the internal NVMe disks with mdadm.
In both models, saturation happens on hardware level (disks, network, etc.) processors and other soft components doesn't impose a meaningful bottleneck even under high load.
Also, yes, many longer jobs are checkpoints and restart where it's left off, but it's not always possible, unfortunately.
Enabling pre-emption in your queues by default and that'll change: after a job is scheduled and run for 1-2 hours it can be kicked out and a new one run instead after the first's priority decays a bit.
* https://slurm.schedmd.com/preempt.html
You can add incentives:
> When would I want to use preemption? When would I not want to use it?
> When a job is designated as a preemptee, we increase the job's priority, and increase several limits, including the maximum number of running processors or jobs per user, and the maximum running time per job. Note that these increased limits only apply to the preemptable job. This allows preemptable jobs to potentially run on more resources, and for longer times, than normal jobs.
We run preemptive queues, and no. Not all jobs are compatible with that. Esp. the code researchers developed themselves.
My own code also doesn't have support for checkpointing. Currently it's blazing fast, but for bigger jobs it might need the support, and it needs way more cogs inside the pipeline to make it possible.
Or IBM's GPFS / Spectrum Scale. Same deal, really, although GPFS is a more complete package.