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.
Problems Connecting The Stats Servers
If you are trying to log onto the stat servers for the first time and are unable to, the most likely cause is that you don't (yet) have an AFS account. AFS accounts are free with the standard computing services package, but they are not set up automatically. See Setting Up Your AFS Access in the access troubleshoting page for how to diagnose and report problems.
For all other access problems, see the overall access troubleshoting page.
New Server Pool In Production, Old Pool Decomissioned
We have converted our service to a new hardware pool that gives us faster performance and allow larger memory footprints. The new pool is available as
scs.dsc.umich.edu or any of the previous aliases.
Connecting to the general pool name 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, connecting to
mario.dsc.umich.edu takes you directly to that particular host in the 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 many instances of a program, you should run about half on each of the two machines in the pool. Running all of them on one machine can use 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, locking up a license and using up resources.
Remember, these machines are a shared service. As a rule of thumb, you should try not to consume more than about 25% of the processing power on any individual host. This is not enforced at a system level; we rely on you to be a good citizen and will let you know if problems arise with your work.
If the machines become heavily loaded, we reserve the right to ramp that percentage down as needed.
The servers in the pool have a memory limit of 24GB per login per user. (By contrast, the old pool had a memory limit of 8GB.) The limits prevent a runaway process from accidentally consuming all of the memory on one of the machines.
Reporting Problems With This Page
To report problems with this page or make suggestions to improve it, please send email to the ITS Statistics and Computing Admins.