Sense data and SCSI Good Status

Pat LaVarre lavarre at
Thu Nov 1 08:01:09 PST 2001

* From the T10 Reflector (t10 at, posted by:
* "Pat LaVarre" <lavarre at>
> ... Don't confuse sense data
> for the completed command

> with sense data that
> may be in the buffer
> provided when REQUEST SENSE
> is explicitly used
> to retrieve sense data.

> ... A tricky point ...

Me, recently I was surprised to hear of a device that, while formatting media, returned the same SK:ASC:ASCQ no matter whether politely polled with auto-sensed op x00 TestUnitReady or rudely polled with op x03 RequestSense ...

... but this device filled out the rest of the sense data more usefully only if polled directly with x03 RequestSense.

This device design choice caused trouble as soon as someone found a (I hear popular FireWire) host too fragile to transport and interpret x03 RequestSense data except when that data arrives via auto sense.

Pat LaVarre

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