[slurm-users] How can jobs request a minimum available (free) TmpFS disk space?

[Ole Holm Nielsen]

We have some users requesting that a certain minimum size of the 
*Available* (i.e., free) TmpFS disk space should be present on nodes 
before a job should be considered by the scheduler for a set of nodes.

I believe that the "sbatch --tmp=size" option merely refers to the TmpFS 
file system *Size* as configured in slurm.conf, and this is *not* what 
users need.

For example, a job might require 50 GB of *Available disk space* on the 
TmpFS file system, which may however have only 20 GB out of 100 GB 
*Available* as shown by the df command, the rest having been consumed by 
other jobs (present or past).

However, when we do "scontrol show node <nodename>", only the TmpFS file 
system *Size* is displayed as a "TmpDisk" number, but not the 
*Available* number.

Question: How can we get slurmd to report back to the scheduler the 
amount of *Available* disk space?  And how can users specify the minimum 
*Available* disk space required by their jobs submitted by "sbatch"?

If this is not feasible, are there other techniques that achieve the 
same goal?  We're currently still at Slurm 18.08.

Thanks,
Ole

-- 
Ole Holm Nielsen
PhD, Senior HPC Officer
Department of Physics, Technical University of Denmark