Flux Allocation Options

A Flux allocation is a reservation for a set of resources which includes CPU cores, RAM, and may include GPUs. Also, an allocation is a component of a Flux resource account for a specific Flux compute service. A resource account, is required to run jobs on Flux. Each resource account may have one or more allocation, in which the allocations may have different sizes, durations, and funding sources. This is true for most Flux compute services except Flux on Demand, since the service does not use reservations but bills for CPU core-seconds used.

All resource accounts, regardless of service, have a list of Flux user accounts that may use the associated allocations. The job scheduling system will attempt to fairly share the available resources between these users’ jobs based on the resources request and the user’s more recent usage history. Users with low recent usage will get higher priority for their jobs, while users with high recent usage will get lower priority.

The most common type of allocation is for standard Flux which has 4 GB RAM for each CPU core. Resources within an allocation may be independently utilized. For example, a 16 core allocation will have 64 GB of RAM, so a job may use almost any combination of resources. If the running jobs use 8 cores and 48 GB of RAM, 8 cores and 16 GB RAM remain available to use, but if the running jobs use all 64 GB RAM, no more jobs can start even if there are cores free in the allocation.

Research Allocations

Research groups that need computation resources should obtain their own Flux allocation but may use the CoE shared allocations to try Flux. It is recommended that the group tries one of their use cases on a trial allocation, which should help determine the size and type of allocation, before they purchase their first allocation.

Allocations can also be obtained for use by multiple research groups across departments, centers, institutes, or other units. A Principal Investigator (PI) may have more than one resource account and should setup multiple resource accounts when necessary. For example a PI may set up the first account for all of their lab members to use for general research and then add additional accounts for specific projects restricted to only those individuals working on the project.

Test/Trial Allocation

PIs can request a one-time, two-week trial allocation, for each type of service, by contacting coe-research-computing@umich.edu. The trial allocations are intended to give PIs, who have never used a specific Flux service, a chance to see if that Flux service is a good resource to use in their work. The trial allocation is limited to 32 cores for standard Flux, 8 cores for Large Memory Flux, or 2 GPU for GPU Flux. These allocations are for the exclusive use of the PI’s research group.

Shared Flux Allocations

The College of Engineering provides two shared Flux allocations: engin_flux and engin_fluxg. These allocations are intended for experimentation and exploration on a small-scale, and they are not intended for large research project or course work.

Course Allocations

Instructors should set up an allocation for each course that requires the use of Flux. Students should use the course allocation for experimentation, assignments and projects associated with the course, and should not use the shared allocations for course work.

Note to Students:

Usually students may not set up their own allocation. Students that need to use Flux as part of a course should ask their instructors about the course allocation. In the case a student needs Flux to conducting research for their advisor, he or she should discuss setting up a Flux allocation with their advisor:

  • Graduate students may want to use Rackham Graduate Student Research Grants to purchase their own, private Flux allocation.
  • Undergraduate student groups should consider Flux for Undergraduates. This service makes unused CPU cores available to a job, but the job will be preempted if higher priority jobs are submitted and need the resources.

Requesting an Allocation

To request a Flux Allocation please send the following information to hpc-support@umich.edu from your University of Michigan email:

  • Type of Allocation (specific Flux compute service):
  • The number of cores needed:
    (If you are requesting a GPU allocation, this is the number of GPUs needed. If you need help sizing your allocation see the Flux sizing page)
  • The start date for the allocation:
  • Number of months for the allocation:
  • The shortcode for the funding source:
  • The uniqname of the authorized signer for the shortcode:
    (If the authorized signer does not make the request, confirmation from the authorized signer is required before the request is processed)
  • A list of uniqnames of people who should be allowed to run jobs under the allocation:
  • A list of uniqnames of people who can change the allocation:


Send questions about any of these Flux allocations to: coe-research-computing@umich.edu