News for UMD High Performance Computing
- 2021 Feb 05
- Due to a cooling failure in the data center housing Deepthought2, the cluster had been shut down for protection from about 8:10 AM to about 9:30 AM. We apologize for any inconvenience.
- 2020 Nov 10
- Part 2 of the virtual MATLAB workshop (scheduled for 11/17/20) has been postponed due to technical problems. When the problems are solved, we will inform the HPC users about the new date (latest in Jan.2021).
ssh login.deepthought2.umd.eduwill now put you on a RHEL8 login node. For now, you can still use
ssh rhel6.deepthought2.umd.eduto access a RHEL6 login node (and
ssh rhel8.deepthought2.umd.eduwill still put you on a RHEL8 node).
- You can still give a
--constraint=rhel8flag to sbatch, etc. to specify that you want your job to go to RHEL6 or RHEL8 compute nodes, but now jobs not explicitly specifying an OS version will default to going to RHEL8 nodes.
Note: The host key for
You can remove the offending key with the command
You can then ssh again. You will likely get a slightly less scary warning from ssh, this time saying it cannot establish the authenticity of the host, and again give a host key fingerprint. If it is the same fingerprint as before or another valid fingerprint in the list valid key fingerprints for login nodes, you can just respond yes and ssh will continue to the login node (and will record the fingerprint for future reference).
- You can ssh to
rhel8.deepthought2.umd.eduto go to a RHEL8 login node. The hostname
rhel6.deepthought2.umd.eduwill point to a RHEL6 login node. Currently
login.deepthought2.umd.eduwill also point to an RHEL6 node, but this will change to point to an RHEL8 login node at some point (probably late Oct/early Nov).
- Both the RHEL6 and the RHEL8 nodes (compute and login) will share a home directory and lustre directories, so you can access your same files from either.
- Both the RHEL6 and the RHEL8 nodes will share the same scheduler. So you can submit jobs for either set of nodes from either RHEL6 or RHEL8 login nodes. You can also monitor jobs from any of the login nodes.
- Your allocations will have access to both RHEL6 and RHEL8 nodes. SUs are
shared across the nodes. So if you have a 100 kSU allocation, you can do any
of the following (but not all of the following):
- Submit 100 kSU worth of jobs to RHEL6 nodes.
- Submit 100 kSU worth of jobs to RHEL8 nodes.
- Submit 50 kSU worth of jobs to RHEL6 nodes, and 50 kSU to RHEL8 nodes
- Submit jobs to both RHEL6 and RHEL8 nodes, such that the sum of the amount submitted RHEL6 and the sum of the jobs submitted to RHEL8 nodes adds up to 100 kSU
- Software will likely be incompatible between the two OS levels, due to differences in system libraries. We have built a new software library for RHEL8, and will be continuing to update during this semester. Please contact system staff if a required package is missing. We are no longer adding new software or upgrading software on the RHEL6 side.
- With respect to software you built, you will likely need to recompile it for it to work on the new system.
- Because of the software incompatibilities, you will likely need to send a job specifically to RHEL6 or to RHEL8 nodes. To facilitate this, we have added "rhel6" and "rhel8" features to nodes to allow you to specify which type of nodes are desired. For now, jobs not specifying a constraint will default to using "rhel6". You should not rely on the default behavior as we will likely be changing it in late October/early November.