From: li@oculus.loni.ucla.edu (James Li)
Subject: 3rd Party Disks (FAQs #35 disktab & #44 HD utility)
Organization: Jules Stein Eye Institute
Date: 22 Jan 93 09:03:44 PST

Re: FAQ #35
Does anyone have any experience with drives that DO NOT have a constant
number of Sectors per Track?  We just bought a Quantum Pro1225 and the Sectors
per Track is between 44 to 92.  What should go in the disktab entry under 
'ns' (sectors per track)?  

Re: FAQ #44
I was told by Apple Tech Support that HD Setup will avoid having to deal
with the disktab file.  Why then (besides the password protection mentioned
below) would one choose to use a different set-up?  Is there an actual
or a potential speed advantage?

Thanks for any information and suggestions.

James Li
li@oculus.loni.ucla.edu

[The rest of this message contains the FAQ entry for Questions 35 and 44]

===
35)  How can I figure out the /etc/disktab entry for my hard disk?

Many hard disk applications will reveal the disk drive geometry for you:
FWB Hard Disk ToolKit and SCSI Evaluator are very good (SilverLining is a bit
wrong on the number of tracks... it includes spares). What you are really
looking for are the total number of cylinders ('nc'), the number of sectors
per track ('ns') and the number of tracks ('nt'). Also, I'm maintaining
a list of /etc/disktab entries. If you have any, send it to me and I'll
add them.

The file will be available via anon-ftp on jagubox.
<<ED: I need _LOTS_ of entries>>

Just a note: the number of tracks ('nt') is equal to the number of heads.

===
44)  I heard the the Installer for 3.0 works on "any" 3rd party hard disk.
     Well, it doesn't on mine!

Well, the Installer will work with any 3rd party disk but there are a few
wrinkles... The HD Setup application in the 3.0 Installer is unique in that
not only does it create A/UX partitions but it also creates the actual file
systems in those partitions (basically it runs 'newfs'). Now if you have
used some other HD utility program (such as SilverLining or FWB HDT) to
create the partitions and then attempt to install A/UX on that disk, the
Installer sees that the partitions are there and then _assumes_ that they
were created by HD Setup and therefore have the file systems already created.
Of course, the file systems don't exist yet, just the partitions, so the
installation fails.

You have a few options:

 a. Run the Installer on a newly formatted disk. This means that HD Setup
    will do all the partitioning (etc...) and the installation will
    proceed. Note that this means you will be "stuck" with the Apple drivers
    whenever you are in the _real_ MacOS Finder.

 b. If you want to use the drivers on your HD utility (for stuff like,
    maybe, password protection of partitions) then you have two (maybe
    three )additional options:

   i. Use 'a' above to install A/UX. Then use your HD utility program to
      "take over" the disk, disabling (or even removing) the Apple drivers
      and installing it's own. Note that if there isn't enough space to
      install it's drivers, most will attempt to "shrink" the MacOS
      partition to make room. Most can do this with no problem, but why
      take the risk... when you partition the disk, leave about 64K
      available as free space.

  ii. Use your HD utility to create the partitions. Then, before you
      run the Installer, run 'newfs' "by hand" to create the file systems
      so that the installation can proceed.

 iii. Use your HD utility to format (etc...) your disk and create
      _only_ the MacOS partition. Now run the Installer. In most cases
      HD Setup will work fine with the driver installed on the disk.
      You can now use it to create the A/UX partitions.

      <<ED: I _know_ this (iii) works with FWH HDT 1.1.x>>

===

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