Info Services > Computing Guide > Cluster Processing

Overview

This document describes acceptable use of NRAO computing facilities for the purpose of calibration and imaging ALMA, VLA and VLBA observations.  The NRAO operates two computing facilities.  The North American ALMA Science Center (NAASC) and ALMA archive are in Charlottesville, Virginia so users of ALMA data will probably want to use the NAASC cluster (cvpost).  The New Mexico Array Science Center (NMASC) and VLA/VLBA archive are in Socorro, New Mexico so users of VLA/VLBA data will probably want to use the NMASC cluster (nmpost).

Users of NRAO computing resources must abide by the Acceptable Use Policy. Sharing of assigned user accounts is not permitted.

Resource request types and prioritization

The NAASC and NMASC have finite computing resources.  In the event of over subscription, resources will be granted in the following priority order:

1.    Archive requests for data retrieval.
2.    Pipeline reprocessing requests to re-run NRAO supplied VLA/VLBA and ALMA pipelines with modified parameters.
3.    Batch (script) submission to execute a user defined pipeline.
4.    Interactive use for direct CASA, AIPS or other interaction.

In the event that all resources are in use, new tier 1 jobs will move to the top of the queue, then tier 2, then 3 and finally tier 4.  NRAO expects roughly 50% of the compute resources to be available for tier 4 interactive use. The distribution of job type is expected to change as more observers adopt pipeline reprocessing and batch processing modes.  

Over time the NRAO will examine finer grained prioritization, particularly within the batch and interactive queues, based on science rank, data size, time since observation or other parameters.

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