RE: iSCSI Autosense

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

David,

If you were to add Autosense emulation at the remote adapter, then should it
be done with ACA emulation as well if tags are supported?  (FCP drives
require Autosense.) The intent of Autosense and ACA is to ensure recognition
of an error condition before continuing operation.

SAM provides for conditional enabling of Autosense if allowed, whereas iSCSI
provides for the conditional disabling of Autosense making Autosense a
required feature.  This would also seem to imply ACA would also be a
required feature.  An effort to achieve for a device which does not
implement ACA.  By requiring Autosense on all devices, does this create a
difficult situation?  Keeping the SAM view of Autosense allows a simple
means of handling these cases.

Doug

> -----Original Message-----
> From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
> Black_David@emc.com
> Sent: Tuesday, August 29, 2000 12:20 PM
> To: ips@ece.cmu.edu
> Subject: RE: iSCSI Autosense
>
>
> > 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.
>
> I believe ACA should have been Autosense in the first question above.
>
> A target adapter (i.e., iSCSI target to SCSI initiator) can
> definitely make
> the translation - in response to a CHECK CONDITION from a device that
> does not support Autosense, it fetches the sense data, clears the
> condition,
> and returns the data as specified by Autosense.  The requirements
> document already contains a statement that older SCSI devices
> may require translations of this ilk.  This is much better than
> expecting the iSCSI initiator to come in and clean things up,
> since the device can't do anything else until this is done, and the
> iSCSI initiator may be some distance away.
>
> --David
>
> ---------------------------------------------------
> David L. Black, Senior Technologist
> EMC Corporation, 42 South St., Hopkinton, MA  01748
> +1 (508) 435-1000 x75140, FAX: +1 (508) 497-6909
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>