Question on RECOVERED ERROR handling

Charles Monia monia at
Thu Aug 3 14:52:02 PDT 1995


I am looking for information on how SCSI-2 devices,
particularly sequential devices, handle a RECOVERED ERROR
condition that has been reported through the return of CHECK

The problem is an apparent conflict between the requirement
for deferred error reporting specified in section
of the SCSI-2 spec (rev 10h, pp 134) and the definition of

The fourth paragraph of that section states:

"If an I/O process terminates with CHECK CONDITION status
and the subsequent sense data returns a deferred error that
I/O process shall not have been executed.  After the target
detects a deferred error condition on a logical unit, it
shall return a deferred error according to the rules
described below...." 

However, according to the description of the RECOVERED ERROR
sense key (see table 69):

"RECOVERED ERROR: Indicates that the last command completed
successfully with some recovery action performed by the
target. Details may be determinable by examining the
additional sense bytes and the information field. When
multiple errors occur during one command, the choice of
which error to report (first, last, most severe, etc.) is
device specific."

These look contradictory to me. In the case of a deferred
error, the standard seems to require the logical unit to
terminate the command without doing any work.  Whereas the
description for RECOVERED ERROR implies that the associated
command has completed successfully.

Given the above, which of the following statements reflects
device behavior?

a) The command has terminated without execution. The state
of the media is unchanged. For a sequential device, the host
must reissue the command without repositioning the media.

b) The command has completed successfully, even though a
CHECK CONDITION status was returned. No error recovery is


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