Dear Slurm-User List,
currently, in our slurm.conf, we are setting:
SelectType: select/cons_tres SelectTypeParameters: CR_Core
and in our node configuration /RealMemory /was basically reduced by an amount to make sure the node always had enough RAM to run the OS. However, this is apparently now how it is supposed to be done:
Lowering RealMemory with the goal of setting aside some amount for the OS and not available for job allocations will not work as intended if Memory is not set as a consumable resource in *SelectTypeParameters*. So one of the *_Memory options need to be enabled for that goal to be accomplished. (https://slurm.schedmd.com/slurm.conf.html#OPT_RealMemory)
This leads to four questions regarding holding back RAM for worker nodes. Answers/help with any of those questions would be appreciated.
*1.* Is reserving enough RAM for the worker node's OS and slurmd actually a thing you have to manage? *2.* If so how can we reserve enough RAM for the worker node's OS and slurmd when using CR_Core? *3.* Is that maybe a strong argument against using CR_Core that we overlooked?
And semi-related: https://slurm.schedmd.com/slurm.conf.html#OPT_RealMemory talks about taking a value in megabytes.
*4.* Is RealMemory really expecting megabytes or is it mebibytes?
Best regards, Xaver