RE: iSCSI Autosense

["Douglas Otis" <dotis@sanlight.net>]

Somesh,

If adapters on a device basis provide access, can one assume such equipment
will support ACA?  If not, is it practical for the adapter to recognize this
limitation and make required translations?  This could be problematic in
less aggressive technologies such as tape, loaders, and the like.  As it has
an impact on error handling, mistakes in this area could be costly.  It
would be nice to assume all devices and initiators support ACA and Autosense
but a network transport does not by necessity exclude devices that do not.

Doug

> -----Original Message-----
> From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
> somesh_gupta@hp.com
> Sent: Tuesday, August 29, 2000 10:17 AM
> To: ENDL_TX@computer.org; ips@ece.cmu.edu
> Subject: RE: iSCSI Autosense
>
>
> If we are looking for consensus on this issue, I agree with Ralph.
> Better to clean up now than implement something that is waste of
> energy.
>
> Somesh
>
> > -----Original Message-----
> > From: ralphoweber@compuserve.com [mailto:ralphoweber@compuserve.com]
> > Sent: Monday, August 28, 2000 8:03 PM
> > To: ips@ece.cmu.edu
> > Subject: FW: iSCSI Autosense
> >
> >
> > Note: Clause numbers reference draft-satran-iscsi-01.txt.
> >
> > There is nothing in the SCSI Architecture that requires the A
> > Flags bit (byte 2 bit 7) described in 3.2 and 3.2.1.  Specifically,
> > the SCSI Architecture does not require a transport to have the
> > ability to disable Autosense.
> >
> > Contingent Allegiance (the target state that follows a CHECK
> > CONDITION in the absence of Autosense) is not a required SCSI
> > behavior.  In fact, Contingent Allegiance is an out dated
> > SCSI behavior that continues to be documented in SAM for
> > backwards compatibility.  Contingent Allegiance is wholly
> > superseded by the Autosense capability.
> >
> > Autosense is dramatically simpler to implement provided the
> > SCSI transport protocol allows for delivery of the sense data
> > in the same packet as the CHECK CONDITION status (as is the
> > case in iSCSI).
> >
> > IMHO iSCSI would be well served by following the precedent
> > set by FCP.  Remove the A bit and state explicitly that all
> > iSCSI devices are required to support Autosense and that
> > all instances of a CHECK CONDITION status shall be accompanied
> > by Autosense data.
> >
> > Note: These changes will also affect 3.3.7, 5.3 and possibly
> > other clauses of the internet draft.
> >
> > Thanks.
> >
> > Ralph...
> >
> >
> >
>