What are allocations and why do I need one?

In the simplest terms, an allocation is a way for us to specify your cut of Alpine’s computational resources. Allocations are referred to as accounts in Slurm’s documentation and are indicated by the --account directive:

#SBATCH --account=______

Allocations are required to run on CURC clusters. They help us keep track of system usage for reporting purposes and to ensure we have enough resources to accommodate all of our users.

FairShare, Priority, and Allocations

Fairshare Scheduling

The idea behind fairshare scheduling is simple, even though its implementation is complex: jobs submitted by people who have underutilized their allocated resources get higher priority, while jobs submitted by people who have overutilized their allocated resources get lower priority.

Level Fairshare

A Level Fairshare (LevelFS) is a value calculated by Slurm’s Fairshare Algorithm. A user’s assigned shares (determined by their allocation) and usage (based on their job history) contribute to their LevelFS value. Information on how to check your LevelFS score can be found here.

Note that if there are no other pending jobs and enough resources are available then your job will run regardless of your previous usage.

Priority Score

When you request resources on Alpine, your job’s priority determines its position in the queue relative to other jobs. A job’s priority is based on multiple factors, including (but not limited to) FairShare score, job age, resources requested, job size, and QOS.


When you receive a Research Computing account you are automatically assigned a Trailhead Auto-Allocation, which grants you a fixed share of ucb-general. The Trailhead is a great allocation for smaller jobs or testing and benchmarking your code. However, if you consume more than your fixed share of ucb-general, your LevelFS will decrease, causing your priority score to decrease. The end result is that your jobs will sit lower (read: longer) in the queue relative to other jobs. One way to combat this is to apply for an allocation.

Alpine Allocation Tiers

In addition to the Trailhead auto-allocation (ucb-general) that all users are awarded automatically, CURC offers two additional tiers to accommodate larger computing needs on Alpine. The Ascent Allocation tier provides users with 250,000 SUs over a 12 month period. The Peak Allocation tier is aimed at projects that will consume between 250,000 and 5,000,000 SUs in a 12 month period. Users may apply for these tiers as described below.

CURC’s tiered allocations are structured in a way such that your jobs are likely to have a higher priority if they are running in Ascent or Peak Allocations than if they are running in a Trailhead Auto-Allocation.

Comparing Trailhead Auto-Allocation, Ascent Allocation, and Peak Allocation Tiers

The following table summarizes the required information, size, approval process, and renewal requirements for each tier.


Individual and group size limits for new and renewed allocations will be reviewed on an annual basis.

Get an Ascent Allocation

Step 1: Fill out the Ascent Allocation Request form. You need to be logged in to Office365 with your CU Boulder account.

Step 2: Look out for an email message from the CURC ticketing system (rc-help@colorado.edu) indicating when your allocation is ready to use.

Get a Peak Allocation

Step 1: Download and complete the Peak Allocation Request Supplementary Information document. You need to be logged into Office365 with your CU Boulder account.

Step 2: Fill out the Peak Allocation Request form. You need to be logged into Office365 with your CU Boulder account. The last question will ask you to upload your completed Peak Allocation Request Supplementary Information document from step 1.

Step 3: Look out for email messages from the CURC ticketing system (rc-help@colordo.edu). User Support will contact you when the proposal is received, during the initial review stages, and when the allocation is ready to use.

Alpine is jointly funded by the University of Colorado Boulder, the University of Colorado Anschutz, Colorado State University, and the National Science Foundation (award 2201538).