...

10 Gb/s ethernet connections to the Internet from login nodes and transfer node. 100 Gb/s EDR Infiniband connection between compute nodes.

Scheduler

Habanero Terremoto uses the Slurm scheduler to manage jobs.

Fairshare

Resource allocation on our cluster is based on each group's contribution to computing cores. The Slurm scheduler uses fair share targets and historical resource utilization to determine when jobs are scheduled to run. Also, within-group priority is based on historical usage such that heavier users will have a lower priority than light users. Slurm uses all of a job's attributes - such as wall time, resource constraints, and group membership - to determine the order in which jobs are run. 

Using job data such as walltime and resources requested, the scheduler can start other, lower-priority jobs so long as they do not delay the highest priority jobs. Because it works by essentially filling in holes in node space, backfill tends to favor smaller and shorter running jobs more than larger and longer running ones.

There is no preemption in the current system; a job in the queue will never interrupt or stop a job in run state.