Nexus/MC2

The previous standalone cluster for MC2's compute nodes have folded into Nexus as of mid 2022.

The Nexus cluster already has a large pool of compute resources made possible through college-level funding for UMIACS and CSD faculty. Details on common nodes already in the cluster (Tron partition) can be found here.

Please contact staff with any questions or concerns.

Submission Nodes

You can SSH to nexusmc2.umiacs.umd.edu to log in to a submission host.

If you store something in a local filesystem directory (/tmp, /scratch0) on one of the two submission hosts, you will need to connect to that same submission host to access it later. The actual submission hosts are:

• nexusmc200.umiacs.umd.edu
• nexusmc201.umiacs.umd.edu

Resources

The MC2 partition has nodes brought over from the previous standalone MC2 Slurm scheduler. The compute nodes are named twist##.

QoS

MC2 users have access to all of the standard job QoSes in the MC2 partition using the mc2 account.

The additional jobs QoSes for the MC2 partition specifically are:

• highmem: Allows for significantly increased memory to be allocated.
• huge-long: Allows for longer jobs using higher overall resources.

Please note that the partition has a GrpTRES limit of 100% of the available cores/RAM on the partition-specific nodes in aggregate plus 50% of the available cores/RAM on legacy## nodes in aggregate, so your job may need to wait if all available cores/RAM (or GPUs) are in use.

Jobs

You will need to specify --partition=mc2 and --account=mc2 to be able to submit jobs to the MC2 partition.

[username@nexusmc200 ~]$ srun --pty --ntasks=4 --mem=8G --qos=default --partition=mc2 --account=mc2 --time 1-00:00:00 bash
srun: job 218874 queued and waiting for resources
srun: job 218874 has been allocated resources
[username@twist00 ~]$ scontrol show job 218874
JobId=218874 JobName=bash
   UserId=username(1000) GroupId=username(21000) MCS_label=N/A
   Priority=897 Nice=0 Account=mc2 QOS=default
   JobState=RUNNING Reason=None Dependency=(null)
   Requeue=1 Restarts=0 BatchFlag=0 Reboot=0 ExitCode=0:0
   RunTime=00:00:06 TimeLimit=1-00:00:00 TimeMin=N/A
   SubmitTime=2022-11-18T11:13:56 EligibleTime=2022-11-18T11:13:56
   AccrueTime=2022-11-18T11:13:56
   StartTime=2022-11-18T11:13:56 EndTime=2022-11-19T11:13:56 Deadline=N/A
   PreemptEligibleTime=2022-11-18T11:13:56 PreemptTime=None
   SuspendTime=None SecsPreSuspend=0 LastSchedEval=2022-11-18T11:13:56 Scheduler=Main
   Partition=mc2 AllocNode:Sid=nexusmc200:25443
   ReqNodeList=(null) ExcNodeList=(null)
   NodeList=twist00
   BatchHost=twist00
   NumNodes=1 NumCPUs=4 NumTasks=4 CPUs/Task=1 ReqB:S:C:T=0:0:*:*
   TRES=cpu=4,mem=8G,node=1,billing=2266
   Socks/Node=* NtasksPerN:B:S:C=0:0:*:* CoreSpec=*
   MinCPUsNode=1 MinMemoryNode=8G MinTmpDiskNode=0
   Features=(null) DelayBoot=00:00:00
   OverSubscribe=OK Contiguous=0 Licenses=(null) Network=(null)
   Command=bash
   WorkDir=/nfshomes/username
   Power=

Storage

All data filesystems that were available in the standalone MC2 cluster are also available in Nexus.

MC2 users can also request Nexus project allocations.