Compaq Computer Corporation, Inc.

Zuohui Zhang

David L Grant

Robert S Gready

John E Dimitroff

Eugene E Freeman

Raymond A Ritter

A network provides a method of virtualizing SCSI semantics onto a non-SCSI transport medium. The network includes a plurality of hosts or initiators, a SCSI bus coupled to a plurality of SCSI devices, and a bridge having a non-SCSI front end coupled to the non-SCSI transport medium and a SCSI back end coupled to the SCSI bus. The bridge provides firmware for performing various techniques for virtualizing certain SCSI semantics to ensure support (proper operation) of the plurality of SCSI devices. Examples of SCSI semantics for virtualizing SCSI-2 semantics onto a Fibre Channel interconnect medium (a non-SCSI-2 transport medium) include reserve/release support, unit attention support, the non-tagged command processing support for the initiators. Reserve/release support is virtualized by implementing virtual command responses to the RESERVE and RELEASE SCSI-2 command using a table for storing Fibre Channel world wide names (WWN) and the arbitrated loop address (ALPA) for the plurality of initiators. Virtual unit attention support is achieved by maintaining alist of initiators and status flags to determine when a unit attention condition needs to be sent to a particular initiator. When a combination of tagged and untagged commands is detected which would violate the rules for mixing such commands on the back-end SCSI bus, any command(s) that would result in the rule violation will be held within the bridge until the currently outstanding conflicting commands have completed.

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Spring, TX, United States of America

Zuohui Zhang