Dense Memory Cluster (DMC)

The DMC at the Alabama Supercomputer Center has 2380 CPU cores and 13 terabytes of distributed memory. Each compute node has a local disk (up to 1.9 terabytes of which are accessible as /tmp). Also attached to the DMC is a high performance GPFS storage cluster, which has 45 terabytes of high performance storage accessible as /scratch from each node. Home directories as well as third party applications use a separate GPFS volume and share 137 terabytes of storage.

The machine is physically configured as a cluster of 8, 20, 36, or 192 CPU core SMP boards. Thirty-nine nodes have 2.5 GHz Intel 10-core Xeon Ivy Bridge processors and 128 gigabytes of memory.  Twelve nodes have 2.1 GHz Intel 18-core Xeon Broadwell processors and 128 GB of memory.  One node has 2.1 GHz Intel 24-core Skylake-SP processors and 6 TB of memory.  Twenty-four nodes have 2.5 GHz Intel 18-core Xeon Skylake-SP processors and 48 GB of memory.

The DMC has 14 NVIDIA GPU (Graphic Processing Unit) chips. These are a combination of: three DMC nodes configured with four Kepler K20m cards each, and one node with two Pascal P100 cards. These multicore GPU chips are similar to those in video cards, but are installed as math coprocessors. This can give significant performance advantages for software that has been adapted to use these processors. Thus the processing capacity of the DMC cluster is:

  • Conventional processing capacity - 135 TFLOPs
  • Single precision GPU capacity - 63 TFLOPs
  • Double precision GPU capacity - 25 TFLOPs


How do I change my password?

  1. Type "passwd" at a prompt in your ssh session window.

  2. Type your old password at the "Old password:" prompt. Choose option 2 to enter a new password.

  3. Type your new password at the "New password:" prompt.

  4. Retype your new password at the "Re-enter new password:" prompt.

How do I get information on commands related to "my_topic"?

  1. The best option is usually to use the search box at the top right of the page on the HPC documentation website at 
  2. Type man -k at a shell prompt.
  3. Review list of commands generated by man -k to find those that seem appropriate.
  4. Type man for each command that you select.

I can't remember my password. How do I get a new one?

Contact the analyst at

Is the supercomputer just for hard science and engineering?

No! Although chemists, engineers, and physicists currently the heaviest users of the supercomputers, we also have biologists, musicians, environmental scientists, business professors, social scientists, and other users. With the growing interest in data-mining applications in a number of fields, we expect the diversity of our user community to increase.

Please contact the HPC staff at (256) 971-7448 or if you are contemplating non-traditional use of the DMC.

I compiled and ran my first big job on the computer, but after a few minutes it died with the message "Cpu limit exceeded". How do I run big jobs?

Interactive jobs are limited to 600 seconds.

  1. Information on how to run your job via the SLURM job queueing system is in the user manual.

  2. Contact the analyst for help at

How do I use X-window based software on the DMC?

The following commands can be used to setup a X-window connection to the DMC from a machine running UNIX X-windows. The commands might be slightly different from a Macintosh or PC with an X-window emulator.

  1. ssh -Y (where user_id is your login)

  2. Type the command

  3. See the HPC documentation website for additional information on how to install and use X-Windows