Dynamically Adjustable Arbitration Scheme

A computer-readable storage medium storing program code for managing device access fairness in a storage area network, the program code for causing performance of a method comprising:

• maintaining a plurality of requestor queues, each requester queue for storing descriptors representing access requests through a link associated with that requester queue;
• maintaining one or more priority rings, each priority ring containing a plurality of requestor slots for storing request entries from the requester queues and managing device access fairness;
• measuring a queue fill count of a particular requestor queue and comparing it to a watermark level;
• and
• duplicating a request entry for the particular requestor queue on a priority ring if the queue depth exceeds the watermark level.

A system for managing device access fairness in a storage area network, comprising:

• a plurality of requester queues, each requester queue configured for storing descriptors representing access requests through a link associated with that requestor queue;
• an arbiter containing one or more priority rings, each priority ring containing a plurality of requester slots and configured for storing request entries from the requester queues and managing device access fairness;
• and
• logic within each of the plurality of requestor queues, the logic configured for measuring a queue depth of the requestor queue, comparing the queue depth to a watermark level, and duplicating a request entry for the particular requestor queue on a priority ring if the queue depth exceeds the watermark level.