Date: Dec 5, 1989                            X3T9.2/89-145 Rev 1

To: X3T9.2 Committee (SCSI)

From: George Penokie (IBM)

Subject: Additional SCSI Qualifiers


We are requesting three ASCQs be added to the SCSI-2
standard.  These three ASCQs allow reporting of conditions in
which the a device wants to recommend that data be
reassigned.  The current ASCs for recovered data and
unrecovered read errors do not have any ASCQs to cover this
condition.

Byte
12 13 DTLPWRSOMC Description

11 0B D      O   Unrecovered Read Error, Recommend Reassignment
11 0C D      O   Unrecovered Read Error, Recommend Rewrite

This ASCQ would be reported when a device has detected a hard
error during a read and does not think that rewriting the
data at the same position will help.  There are cases on some
devices that by rewriting the data the hard error will be
permanently removed.  On these devices the recommended procedure
would be:

  If sense code = 11 0C  then  rewrite the data
  If sense code = 11 0B  then  reassign the LBA

Byte
12 13 DTLPWRSOMC Description

17 07 D      O   Recovered Data without ECC, Recommend 
                 Reassignment
17 08 D      O   Recovered Data without ECC, Recommend 
                 Rewrite
18 05 D      O   Recovered Data with ECC and/or Retries,
                 Recommend Reassignment
18 06 D      O   Recovered Data with ECC and/or Retries,
                 Recommend Rewrite

These ASCQs would be reported when a device has detected that
data at a location is trending toward becoming a hard error
and therefore should be reassigned.  One way for devices to
determine when to report these ASCQs would be to keep
historical error rate data.