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From: werner@cs.utexas.edu (Werner Uhrig)
Newsgroups: comp.sys.mac.announce
Subject: Stacker problem explained, and how to avoid/fix/survive it
Message-ID: <9311200157.AA02281@cs.utexas.edu>
Date: 19 Nov 93 14:07:18 GMT
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        [ the submitter wished to remain anonymous.  thanks anyway! ]


     Stacker for Macintosh 1.0 Apple HD SC Setup 7.2 with Stacker

			      Background
Apple HD SC Setup 7.2 disk driver with the SCSI Manager 4.3 toolbox
item supports a different, faster method of handling disk access
called asynchronous communication.  The first shipping version of
Apple HD SC Setup 7.2 had trouble handling the older synchronous calls
from other drivers. These drive communications problems made it
incompatible with Stacker for Macintosh.

Using Stacker for Macintosh on a Macintosh running Apple HD SC Setup 7.2
can cause data loss. For problems to occur, the Macintosh must also be
using the new SCSI Manager 4.3 either as an added extension, an updated
System file or as part of the hardware in the newer systems like the
Centris 660 AV and the Quadra 840 AV.

Apple quickly responded to this problem and has released an update of
Apple HD SC Setup.  The new release, Apple HD SC Setup 7.2.2 is available
on electronic forums such as Compuserve and Apple Link in the form of an
update as well as your local Apple Dealer. This version is compatible
with Stacker for Macintosh.


If you have not already installed Stacker: 

Get the updated version of Apple HD SC Setup, version 7.2.2 or later,
or a third party SCSI Driver utility and update your SCSI driver before
installing Stacker.


If you have already installed Stacker on a system using Apple HD SC
Setup 7.2 do not attempt to remove Stacker or make changes to the
disk!  Attempting to make changes or run a disk repair utility while
Apple HD SC Setup 7.2 can cause irreversible data loss.
The driver must be updated before any changes are made to the system.


To update the SCSI Driver: 
1. Start up the Macintosh from the appropriate Stacker for Macintosh
   diskette
2. Select "Disconnect Stacker" from the "Disk" menu bar.
3. Select the SCSI device  that is using the Apple HD SC Setup driver.
   Follow the Disconnect instructions 
4. Exit Stacker for Macintosh
5. Start up from a Disk Tools diskette with Apple HD SC Setup 7.2.2
   (or a third party driver)
6. Select to Update or Install the Driver.
   Follow the instructions indicated for the Driver application
7. Restart the Macintosh 

After the SCSI Driver is updated to Apple HD SC Setup 7.2.2 or a third
party driver, the disk should be accessible. If not, try Removing Stacker
and re-installing it. If you are unable to Remove Stacker, try running a
recovery utility, then reformat the disk. 

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