Re: iSCSI: SCSI Response Hdr - Sense Data Length

["Julian Satran" <Julian_Satran@il.ibm.com>]

The SCSI response needs anyhow a separate handler.
In most of the cases the data segment will contain nothing.
When it contains something it may be sense or response (or sometime in the future both).

So in most of the case you will have to check one field and only on exceptions two.

Julo

Michael Schoberg <michael_schoberg@cnt.com> Sent by: owner-ips@ece.cmu.edu 04/22/2002 08:42 PM Please respond to Michael Schoberg

To:        "IPS Reflector (E-mail)" <ips@ece.cmu.edu>         cc:                 Subject:        iSCSI: SCSI Response Hdr - Sense Data Length

A question concerning the iSCSI - SCSI Response headers (op-0x21).  When the
target sends it with a DataSegmentLength > 0, it must automatically include
a two-byte sense data header preceding any response data.  This means all
response data will be offset by this two byte header even if the
sense-length is zero.  Why wasn't the sense data length put in the byte 20
range of the response (currently marked reserved)?  This would've avoided
the extra work for initiators to have to handle response data for this PDU
type differently from the others.  Essentially, this forces another header
handler on the initiator side for the two header bytes describing the sense
data length.