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Operating System - Tru64 Unix
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Alpha DS20 and ES40 interface to QLOGIC SCSI adapter

Alice Daniel
Frequent Advisor

Alpha DS20 and ES40 interface to QLOGIC SCSI adapter

I have a custom device interfacing with a QLogic SCSI Host Adapter (KZPBA-CA PCI to Uutra SCSC\I)in an Alpha Server DS20 OS TRU64 v4.0F. My device is a FAST-10 narrow interface. I have a custom driver to manage my device. I send a command to READ DATA then perform a REQUEST SENSE (with 18 bytes for returned data buffer)after each data buffer is received, if the data buffer has a status of "check condition".

I find, using a SCSI analyzer, that the HBA seems to be sending its own REQ SENSE command (with 254 bytes data buffer) IN FRONT of mine! Therefore, I get ReadDataScan - followed by UNSOLICITED REQSENSE (takes approx 6ms to complete) - followed by my REQ SENSE (approx 1ms to complete). I am running SCSI extenders with approx 1000m of Single Mode Fiber between the Alpha Server and the device. The extra time to service the UNSOLICITED REQ_SNS cmd is causing me to drop data.

I used the eeromcfg.exe utility to modify various parameters,but none have disabled this unwanted command.

Does anyone have any idea how to better control the bios to disable the card's sending of a REQ_SNS on check-condition?