Hallam, Ken MV
KHallam at po2.mv.unisys.com
Wed Sep 25 11:06:00 PDT 1996
* From the SCSI Reflector (scsi at symbios.com), posted by:
* "Hallam, Ken MV" <KHallam at po2.mv.unisys.com>
There is a situation operating tape drives, (or any removable media device)
wherein a new device will read, but not write older generation media. Only
newer media can be both written and read on this device. The question for
our mavens is thus: Given a new device that has older media mounted, what is
proper SCSI etiquette to use as a response when the host sends down a WRITE
command to media than cannot be written?
A. Check Condition 02, Sense Key 5h, (Illegal Request)) ASC/ASCQ 30h/05H
(cannot write medium, incompatible format)
B. Check Condition 02, Sense Key 3h, (Medium Error), ASC/ASCQ 30h/05h
The Sense Key is the area of contention. A Key of 5 says illegal request,
but the SPC definition indicates that this code is related to errors in
"bits in the CDB" and since there were no invalid bits in the CDB, this code
seems less than perfect.
A Key of 3 is defined as a Medium Error, but this is normally taken as
pointing a specific defect on the recording media itself, which is not the
case here thus, Sense Key 3 does not seem to fit either.
We have vendors who argue for either Sense Key value. Is there anything
approaching a consensus out there?
ken.hallam at mv.unisys.com
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