Examples of using LUNs other than 0

Brian A Berg bberg at bswd.com
Fri Mar 29 15:34:49 PST 1996

* From the SCSI Reflector, posted by:
* Brian A Berg <bberg at bswd.com>
Regarding examples of the use of LUNs other than 0 on SCSI peripherals,
Pioneer 6-disc mini-changer CD-ROM drives use LUNs 0-5 to access each of
the 6 discs; hence, a reference to a LUN different from that of the
previous command's causes an implicit change of media.

Various other vendors have also done what Pioneer did.

Fujitsu and other vendors have tape drives with autochangers, where LUN
0 refers to the drive and another LUN (sometimes 4) refers to the auto-
changer.  Hence, LUN 0 is PDT=1 (sequential access -- tape) and LUN 4
is PDT=8 (medium changer), and so tape commands go to LUN 0 and medium
change commands go to LUN 4.

Due to operating system file system size restrictions, disk vendors
could implement LUNs in some programmable fashion to access 2GB or
4GB per LUN.  This could help now that companies like Seagate are
announcing drives with 23GB of capacity.

Is anyone out there thinking along the lines of the above?  Becky: Is
this what you were thinking of?
  Brian A. Berg           E-mail: bberg at bswd.com
  Berg Software Design     Voice: 408.741.5010
  P.O. Box 3488              FAX: 408.741.5234
  14363 Saratoga Avenue, Suite 200-B
  Saratoga, CA 95070 USA   Focus: software consulting: SCSI, optical storage

More information about the T10 mailing list