ITS Statistics and Computation Service
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ITS Statistics and Computation Service

The ITS Statistics and Computation Service (SCS) offers a set of Linux-based servers to regular students, faculty, and staff of the University of Michigan to run computationally intensive or long-running programs. These vary from using mathematical and statistical programs to compiling and running custom programs.

Connecting to the Server

If you have the University's standard computing services that is provided to all registered students, regular faculty, and regular staff, you can use the SCS. Access to the SCS is included in the package.

You must use ssh (secure shell) to connect to the SCS, and you must use scp (secure copy) or sftp (secure ftp) to copy files to and from the server.

New Server Pool Means Two Ways to Connect

We are in the process of upgrading our stats server pool. The new pool will give us faster performance and allow larger memory footprints.

The new pool is now the default when you try to access scs.itd.umich.edu. If you need to use the old pool, you can still reach it by the old individual machine names or by using scs-old.itd.umich.edu. The old pool will remain available through the end of winter semester 2014. It will be decomissioned shortly after that.

Connect to your intended pool via the hostnames below:

SCS Pool Hostname
Legacy Pool scs-old.itd.umich.edu
New Pool scs.gpcc.itd.umich.edu

Connecting to the hostname will log you into one of the machines in the SCS pool. Depending on the program you're running and whether you're writing to the local disk, you may need to log into the same machine multiple times. To determine which machine you've logged into, type

hostname

at the command prompt.

To connect to a specific machine, point your SSH client at the hostname for that machine. For example, ssh'ing to mario.dsc.umich.edu would take you directly to that particular host in the new pool.

Long-Running Jobs and Local File Space

For information about local file access for long-running jobs, and other ways to make running long jobs easier, please read the Long-Running Jobs page.

We get a weekly report from each machine in the SCS pool about jobs which seem to be idle for more than four weeks or which may have run wild. We examine those jobs and contact the job owners to determine if the jobs are running correctly.

Resource Utilization and Memory Limit

Because there are a limited number of SCS machines with a limited amount of memory, it is important to be conscious of your use of resources on these machines. Please do not run many instances of the same program on one machine. If you need to run four instances of a program, you should run one instance on each machine in the pool rather than running all of them on one machine, and using up all of the CPU and memory available on that machine. Also, when you are finished with a job, please make sure that you don't leave it running. An unattended process can run for weeks or even months, using up resources.

The new pool has a memory limit of 24GB per login per user. The old pool has a memory limit of 8GB per login per user. The limits prevent a runaway process from accidentally consuming all of the memory on one of the machines.

If you have comments, questions, or suggestions please email them to scs-admins@umich.edu.