[Jlab-scicomp-briefs] change to exclusive farm nodes

[Sandy Philpott]

Dear JLab farm users,

At the recent meeting with Physics Computing Coordinators, it was agreed to reconfigure the batch nodes without exclusive-only nodes:

>From the meeting minutes:  "Physics codes are becoming multi-threaded, but not enough to fill modern nodes efficiently (i.e they can't use 48 threads on the 2014 24-core nodes, nor could they use 64 threads on the 2016 32-core nodes). Best solution: shrink the exclusive nodes, and implement non-exclusive nodes for 16 core (thread) jobs.  The 2014 nodes would be advertised as 48 slots for 3 jobs, and the 2016 nodes will be advertised as 64 slots for 4 jobs."

This way, all farm nodes can run the diverse mix of jobs without having to carve out specific exclusive-only nodes to match the ever-changing job mix, and cores won't be wasted when a 16 core job lands on a 24 core node.

In short, continue to specify the appropriate job resources for cores and memory, and the batch system will schedule accordingly.

Regards,
Sandy