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    AST RESEARCH, INC.         TECHNICAL BULLETIN # 1231                6-21-95

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    DISK DRIVES DROP OFF-LINE DURING POST

    PROBLEM

    During POST, a physical disk drive can drop off-line.  The following text
    message is displayed on the system console when this symptom occurs:

    Warning:  1 SCSI device is critical
    Warning:  The following SCSI device is dead:
    		Chn x, Tgt y

    NOTES

    1.  "x" is the channel on the DAC960 and "y" is the identification
        number of the SCSI disk drive.

    2.  This problem is very intermittent and does not occur very often.

    CAUSE

    The Attention button (ATTN) is pressed during POST.  Pressing the button
    forces a shortened POST memory test which can aggravate the DAC960
    controller when it is in the process of initializing the disk drives.

    SYSTEMS AFFECTED
    AST PART NUMBER AND DESCRIPTION

    520092-XXX      MANHATTAN SMP 486DX/50
    520155-XXX      MANHATTAN SMP PENTIUM/60

    PARTS AFFECTED
    AST PART NUMBER AND DESCRIPTION

    230355-XXX     CONTROLLER DAC 5-CHANNEL
    221134-001     FRU DAC5 HD CTRL

    SOLUTION

    Do not press the "ATTN" button during POST.

    ADDITIONAL NOTES

    1.  If the disk sub-system is configured as a redundant RAID (RAID levels
    one, five or six) and the text message is displayed during POST, the disk
    drive can be rebuilt after booting into the operating system.  See the user's
    documentation to review the procedure.

    2. If the symptom continues to occur even when the "ATTN" button is not
    pressed, contact AST's Technical Support at (800) 727-1278 for
    troubleshooting assistance.