Allocation of SUs

What are SUs?

Service units (SUs) represent units of time on MSI’s HPC resources, and your MSI group will need an allocation of SUs before you can run jobs on these resources. SUs can be used on Itasca, Calhoun, and Cascade.

Do I need SUs?

SUs are required to run jobs on Itasca, Calhoun and Cascade. If you are not using these machines, you do not need SUs. (The lab queue does not require SUs)

How many SUs will I need?

Please see the SU Allocations section of the HPC policies & procedures page for assistance in computing the correct number of SUs. If you have never used SUs, please request an initial allocation of 20,000 SUs and then run some jobs to see how many SUs your typical jobs consume on the HPC resource of your choice.

How do I get SUs?

PIs and group administrators are authorized to request SUs. 

New SU Allocations

At any time, groups that do not have an SU allocation may request an initial allocation of 20,000 SUs to port their workflows and discover the benefits of computing on the HPC systems. Interested groups should send the following information to
1. Number of SUs you are requesting (20,000 in this case).
2. A brief summary of the work you plan to do with the SU allocation.
3. Briefly explain how you determined the number of SUs to request. (It is sufficient to indicate that this is your initial SU request.)

Please also indicate if you are seeking assistance from an MSI consultant

Once a group's workflow functions on the HPC systems, it should be clear how many SUs will be required for a year. We request that PIs and group admins closely monitor the progress of transition to the HPC and submit a Midyear Supplemental Allocation request if necessary.


Generally, SU Renewals are requested during the fall for the following calendar year. This request is part of the annual MSI renewal process and is submitted using the myMSI renewal form. 

Midyear Supplemental Allocations may be requested. These requests are reviewed three times per year. The deadlines for these requests are April 1, July 1, and October 1. To request a supplemental allocation during the year, please send the following information to

  1. Number of additional SUs requested:
  2. Brief summary of work completed so far during the current period.
  3. Brief summary of work to be carried out if the additional SUs are granted.
  4. Briefly explain how you determined the number of SUs to request.
  5. Additional information (optional).

Peer Review

Requests for 50,000 or fewer SUs are reviewed by MSI staff. Requests for more than 50,000 SUs are reviewed by the HPC Allocation Committee. The committee meets in late fall to determine allocations for the following calendar year. The committee also meets in April, July, and October to review midyear requests. All peer review is conducted on the basis of the following criteria:

  • The quality of the proposed research and the importance of the proposed work in its own field 
  • The research project's need for Supercomputing Institute resources and the Principal Investigator's past usage of resources 
  • The Principal Investigator's ability as judged by past accomplishments, external funding, or other evidence of successful peer review or future potential
  • The Principal Investigator's contributions to the MSI Research Reports Series 
  • The relevance of the work to the University's missions of education, research, and technology transfer 


The deadline for requesting SUs for the next year is November 1. The SU request is included in the MSI renewal form. Ideally, the resulting allocation will include enough SUs to provide for your group's HPC needs through the whole year. If you do find that you need a midyear supplemental allocation, the deadlines for requesting these are April 1, July 1, and October 1.

More details

Further information about SU accounting and monitoring SU usage is available.