SCSI Surrogate Mode?

Paul_A_Suhler at Paul_A_Suhler at
Wed Oct 13 15:17:34 PDT 1999

* From the T10 Reflector (t10 at, posted by:
* Paul_A_Suhler at
Hi, everyone.

It has been suggested to me that a "SCSI Surrogate Mode" is defined by a
SCSI-3 spec.  In this mode of operation, a removable-media drive (e.g.,
tape) has a serial connection to the media changer in which the drive is
installed.  The changer has no SCSI (or Fibre Channel) interface itself.
An initiator sends a media changer command to the drive, but at LUN 1, and
the drive passes it over the serial connection to the changer.  When the
command is finished, the changer sends status to the drive, which sends it
to the initiator.  To the initiator, the target looks like a drive with an
independent media changer, i.e., a loader.

The point of this would be to allow a low-cost changer by saving on a
SCSI/FC interface.

The latest SAM-2 and SPC-2 seem to contain no instances of "surrogate," so
I'm not inclined to believe that it is defined there.

Does anyone know whether this concept has been considered for



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