FCP_DL too small

Neil Wanamaker neil.wanamaker at finisar.com
Mon Nov 1 07:12:16 PST 2004

* From the T10 Reflector (t10 at t10.org), posted by:
* "Neil Wanamaker" <neil.wanamaker at finisar.com>
03-393r3 proposes posting a check condition when FCP_DL is too small,
together with an indication that
there are illegal fields in the CDB.

This proposal makes no distinction between a mismatch between the
transfer length contained in the CDB 
and FCP_DL, and a mismatch between FCP_DL and the media record.

While the proposed change is not unreasonable in the first case, it
appears excessive in the second.

Since the days before there was a SCSI, a read of fewer bytes than the
tape blocksize is legal and results
in an indication of residual data. If  "the application client often is
not informed of the error", this seems to 
be a failing in the driver, rather than the architecture; complete
information is presented to the ULP.

Invoking a recovery procedure (as would be the result of a check
condition) seems inappropriate.

Neil Wanamaker
neil.wanamaker at finisar.com
512.670.7303 (O) 

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