Proposal Review
Details on the review process for medium and large allocation requests by the MRAC and LRAC, respectively, can be found in the NSF Resource Allocations Policies.
In short, a successful MRAC or LRAC proposal will clearly describe three criteria to permit evaluation of the resource request: Computational Methodology, Appropriate Use of Resources, and Efficient Use of Resources. PIs also have the opportunity to appeal the decision of the review committee.
The review process for Development Allocations is not rigorous, since one of its functions is to give new users a trial period. However, these requests may be denied or scaled back if the requested machine is not suitable for the proposed research or is heavily oversubscribed; if a PI already has access to SDSC resources through a separate account; or if the PI does not meet the eligibility requirements.

