                                                             Last Revised
    AST RESEARCH, INC.        TECHNICAL BULLETIN # 1728          06/10/97

    TITLE:  Seagate SCSI Hard Drive Differences

    ISSUE

       The Seagate two and four GB hard drives, part numbers ST32430N
       and ST15230N, originally used in the Manhattan P and V series
       servers, are no longer available. These drives have been replaced
       by the Seagate ST32171N and ST34371N drives which are narrow
       Ultra SCSI drives.

       Although the newer Ultra SCSI drives have been tested and are
       compatible as a direct replacement (for factory-qualified AST
       configurations), there are minor jumper differences between the
       new Barracuda drives and the older Hawk drives. Those who are
       familiar with the older drives should take extra care when
       setting the jumpers on these new drives.

       Pay particular attention to the "Parity" jumper.  On the
       previously qualified drives, this was a "Parity Enable" jumper.
       On the new drives, the corresponding jumper is "Parity Disable",
       and therefore should not be installed.

       The other major difference is the attachment of the SCSI ID
       cable. This cable attaches from the tray edge card to the front
       header connector on the drive. The arrangement of the pins on the
       Barracuda is opposite from that on the Hawk model.

                                             _____  SCSI ID jumpers
                                            /
       |                                   ^       |
       |     Hawk (front)          ______ / \      |
       |__________________________|______|::::::___|
                                          421

                                                _____  SCSI ID jumpers
                                               /
       |                                      ^    |
       |     Barracuda (front)     ______    / \   |
       |__________________________|______|::::::___|
                                             421

       This issue affects all Manhattan P and V series servers.

    BACKGROUND

       N/A

    ACTION

       N/A

    NOTES

       Although the narrow Ultra SCSI drives can be considered a direct
       replacement into a RAID built from standard drives, the reverse
       is not true.

    TAN TPR 17530JB

    ---------------------------------------------------------------------
    The information in this data sheet is subject to change without
    notice. AST Research, Inc. shall not be liable for technical or
    editorial errors or omissions contained herein; nor for incidental or
    consequential damages resulting from the furnishing, performance,
    or use of this material. This material contains information protected
    by copyright. No part of this material may be reproduced in any form
    without prior written consent from AST Research, Inc.
    All rights reserved.
    ---------------------------------------------------------------------
    Template Rev 02