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From: garyb@SSD.CSD.HARRIS.COM (Gary Barton)
Newsgroups: comp.periphs.scsi
Subject: Re: SCSI error -- medium changed in drive
Message-ID: <1677@travis.csd.harris.com>
Date: 5 Dec 90 16:17:43 GMT
References: <1604@travis.csd.harris.com> <129885@jake.encore.com>
Sender: news@travis.csd.harris.com
Organization: Harris Computers Systems Division, Fort Lauderdale,FL
Lines: 42

In article <129885@jake.encore.com> wcarroll@encore.com (Mr. New Dad) writes:
>> 
>> Most CCS disk drives use the same additional sense code to indicate a
>> device was reset or the media may have changed.
>>
>CCS specifies sense code 0x28 as "Media has changed" and sense code
>0x29 as "Device has been reset". If you have a drive that uses ASC 0x28
>to indicate a reset, then it does not follow the CCS spec and should not 
>be advertised as a CCS drive.
>

I stand corrected with regard to my statement that most CCS drives
exhibit this behavior.  I should have said that some drives whose
vendors claim CCS or SCSI-2 compliance actually use the ASC 0x29 to
indicate both conditions, with ASC 0x28 reserved, or assigned to a
different error condition.  Both CCS recommendations and the
preliminary SCSI-2 standard indicate that ASC 0x28 is assigned to
"medium changed", and ASC 0x29 is assigned to a "reset" condition.

>I have never encountered a drive that displays the behavior you state.
>

The Cipher st150s series of 1/4" cartridge tape drives cannot
distinguish between these two sense conditions.  The Cipher model
st150s2 (so named for it's supposed SCSI-2 compliance) uses ASC 0x29
for both conditions, with ASC assigned to an entirely different error.
However, an examination of a couple of other removable media devices
(Maxtor Tahiti, Archive cartridge tape, etc) yields behavior that does
in fact conform to the standards.  I do recall seeing other devices
that exhibit this objectionable behavior, but I can't remember exactly
which units they were.  I guess I have seen too many OEM manuals over
time, and now they are all running together.  I'm not sure if Cipher's
embedded controller was their own design, but if it was not, you can
bet that it can be found in other cartridge tape drives as well, and
those units will most likely exhibit this same behavior.

+--------------------------------------------------------------+
| Gary Barton               | Systems Software Development     |
| Lead Engineer             | Harris Computer Systems Division |
| garyb@csd.ssd.harris.com  | Ft Lauderdale, Florida           |
| uunet!hcx1!garyb          | (305) 974-1700                   |
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