Allocation Reductions

Projects that do not use their allocation effectively in the first three quarters of the allocation year will have some of their allocation returned to the reserve pool of their respective DOE Office of Science Program to be redistributed to other projects.

Time must be redistributed because many projects fall behind early in the year while others run low on time quickly. This allows the system to be productively used throughout the year while reducing the otherwise long queue wait times later in the year. 

The issue is illustrated in the table below, which shows the median project usage throughout AY2023 and is typical of most years.

The removed time is returned to the appropriate program reserve for DOE program managers to redistribute at their discretion. The allocation reductions allow DOE program managers to strategically reallocate time to projects that can use the time earlier in the year. 

We realize that not all projects will use their allocations at a steady pace throughout the year. Therefore, when projects apply for an allocation, they are asked to estimate their quarterly usage. Allocation reductions are made relative to those estimates. (If the aggregate estimates are too heavily backloaded, NERSC will work with users and program managers to address the situation early in the year.)

Projects will not be subject to reductions in the first 60 days following their creation. 

ALCC, Director's Reserve, Exploratory, and Educational projects are exempt from this reduction. However, ALCC has its own allocation reduction scheme, and the Director's Reserve program may make reductions at NERSC's discretion.

Allocation Year 2025

The following schedule will be used for Allocation Year 2025 (which runs from January 15, 2025, through January 14, 2026).

We will use the forecasted computer usage values entered in the AY 2025 ERCAP requests. If you selected "I plan to use resources consistently throughout the allocation year, " your quarterly usage was set to 25% per quarter. If you selected "My usage will vary throughout the allocation year, " we will use the percentage of usage you entered for each quarter. 

This reduction scheme will apply to both CPU and GPU allocations each but will be handled separately.

DOE allocation managers will review requests for exemptions. Project Principal Investigators, PI Proxy, or Project Resource Managers can request exemptions by creating a ticket at https://help.nersc.gov and including justification for the exemption. They must submit the request at least two weeks before the reductions are scheduled to take effect. 

On April 16, 2025:

• We will calculate the Expected Usage as: Expected_usage = initial_allocation*Q1% entered in the ERCAP request.
• Then, if the actual usage is less than the Expected usage, we will remove time using the formula: 
  • If usage<expected_usage, reduce by 1.0*(expected_usage-usage)
• For example:
  • If the Initial Allocation is 1,000 Node hours and the Q1% in ERCAP = 25%, then the Expected Usage = 250 Node hours
  • If the Actual Usage is 50 Node hours, then the amount removed will be: 1.0 * (250 - 50) =  200 Node Hours

On July 16, 2025:

• The calculation for the Expected Usage for the 2nd Quarter: initial_allocation*(Q1% + Q2%) entered in ERCAP request
• Then, if the actual usage is less than the Expected usage, we will remove time using the formula: 
  • If usage<expected_usage, reduce by 0.75*(expected_usage-usage)
• For example:
  • If the Initial Allocation is 1,000 Node hours and the Q1% in ERCAP = 25% and the Q2% in ERCAP = 25%, then the Expected Usage = 500 Node hours
  • If the Actual Usage is 100 Node hours, then the amount removed will be 0.75 * (500 - 100) = 0.75 * (400) = 300 Node Hours

On October 15, 2025:

• The calculation for the Expected Usage for the 3rd Quarter: initial_allocation*(Q1% + Q2% + Q3%) entered in ERCAP request
• Then, if the actual usage is less than the Expected usage, we will remove time using the formula: 
  • If usage<expected_usage, reduce by 0.5*(expected_usage-usage)
• If a project that was created in January has zero usage, 100% of its allocation will be removed and returned to the DOE reserve.
• For example:
  • If the Initial Allocation is 1,000 Node hours and the Q1 % in ERCAP = 25% and the Q2% in ERCAP = 25% and the Q3% in ERCAP = 25%, then the Expected Usage = 750 Node hours
  • If the Actual Usage is 150 Node hours, then the amount removed will be: 0.5 * (750 - 150) = 0.5 * (600) = 300 Node Hours