Re: Here's a IIgs HD question...

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <Pine.SUN.3.91.951101215949.29476C-100000@garcia.efn.org>,
Jason Lewis  <jbl@efn.org> wrote:
> I recently inherited a IIgs from a friend who is working soley on the Mac 
> now. With it came a Transwarp GS card, 4 megabytes of memory and a 100 
> Meg Quantum HD. The HD is partitioned into 2 30 meg and 2 20 meg 
> sections. Before I recieved the computer, the second partition developed 
> a glitch somewhere... And so I don't use it. But someone told me all I 
> had to do was "low level re-format it" and that would fix it. Is anyone 
> willing to give me an explanation on what this involves?

First, define "glitch".  What is the exact error message you get when
trying to use the damaged partition?

It could be a very simple data corruption problem, such as the
directory being damaged.  This can be fixed by running a volume repair
utility, or if you don't actually want any of the data that was on the
partition, you can just "erase" it and it should be usable again.

If in doubt, try doing a "verify" on the appropriate partition from
Finder.  This performs a block-level read of every block on the
volume.  If this reports no errors, then there is nothing physically
wrong with the disk, and it should be possible to erase the partition
and re-use it.

The "verify" operation only confirms that the partition can be read.
It might have a fault that prevents it from being written to.  This
cannot easily be fixed without reformatting the hard drive.


It is not generally possible to do an actual "low level format" of a
SCSI hard disk - the SCSI interface provides a simple FORMAT command,
and it is up to the drive manufacturer to determine what this actually
does.  On older drives, it might do a low-level format, but with most
drives it just verifies that every block on the disk is readable
and/or writeable.  Most modern drives have an automatic mechanism to
"spare out" blocks that appear to be damaged (there is a pool of spare
blocks for this purpose).

If you do want to try reformatting the drive, on the off-chance that
it will fix something, it is very important to note the following:

  If you reformat the drive, you will lose ALL data on ALL partitions
  of the drive.  If you want to keep any of it, it is vitally important
  that you do a backup of all the necessary data before trying to
  reformat the drive.

The procedure for reformatting the drive varies depending on the SCSI
card.  For an Apple SCSI card on a IIgs running GS/OS, use the
following procedure:

1. MAKE SURE YOU HAVE A BACKUP OF THE HARD DRIVE!  Note that it is
   safer to have a "file" backup, rather than a "disk" backup - the
   following procedure involves repartitioning the drive, and you
   may end up with slightly different partition sizes.  You will not
   be able to restore a "disk" backup unless the partition contains
   exactly the same number of blocks.

2. If you don't have a bootable system disk on floppy (with the SCSI
   drivers installed on it), create one using the System 6.0.1
   Installer ("Easy Update" on a blank 800k disk is sufficient).

3. Make sure you have a copy of "Advanced Disk Utility" on floppy.  It
   is on the "SystemTools1" disk in the System 6.0 and 6.0.1 disk sets.

4. Boot from the system disk with the SCSI drivers.  Once you get to
   Finder (or your preferred program selector), launch Advanced Disk
   Utility. 

5. Select any partition of the hard drive, then click on the "Partition"
   button.

6. Delete all of the partitions except the first one.  It doesn't matter
   how big this single partition is.

7. Click on the "Partition" button.  After confirming this operation,
   Advanced Disk Utility asks if you want to reformat the hard drive.
   Use this option.  It will probably take several minutes.

8. Once you get back to the main menu of A.D.U., go back into the
   "Partition" section, and create the desired partition sizes.  Once
   you have the drive configured as desired, click on "Partition" and
   follow the prompts.

9. Reinstall the system software on the hard drive, and restore any other
   backed up files that you want.

> Second question - Recently, my HD's power supply went *POP* and it works 
> no more... The power supply is in the case with the HD, and I was quoted 
> $95 to have it repaired at my local computer store. My question is this - 
> Is there a cheaper alternative that anyone knows of?

It might be cheaper to simply replace the drive enclosure.  That is
about the price I would have to pay for a new case (complete with
power supply).



-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand