Partitioning hard disk and other horrors

[Marc T. Kaufman]

In article <4402 at sdcc3.ucsd.EDU> ss60ubu at sdcc3.ucsd.edu.UUCP (ANDREW MICONE) writes:

>Help! here's the problem.

>I have a Rodime 100meg drive, and A/UX 1.0 on an 80SC.  The latest
>version of the Rodime installer allows you to partition for A/UX
>automatically. Using dp on the drive reveals five partitions, one
>for the Rodime driver, one for HFS, and 3 for UNIX.  The three for
>unix consist of the regular apple unix partition, the partition
>table partition, and a scratch partition.  The logical size for
>these partitions all registers as zero upon observation, here are
>the questions:

>1) Do I need the latter two partitions, the System Manager's notes
>gave me the impression you only needed one partition when using the
>drive as additional data space.

You need the Partition-Map partition, since that IS the partition map.
once that is allocated, zero-entries don't take any (other) space on the
disk. (e.g. the Scratch partition).

>2) What do I set the logical size to? I can't do a mkfs on the drive
>without setting it, but I don't know what to set it to since I can't
>determine how much space the other two unix partitions take up, nor
>exactly the size of a block (I read in one place it was 512 bytes,
>and off of the mkfs command that it was 1024 bytes).  Where can I
>get the block size from? I have the disk partitioned for 50megs HFS
>and 50megs A/UX.

The PHYSICAL size of the disk (number of 512 byte sectors) is stored in
PHYSICAL sector 0 of the disk, in the second long word.  You can allocate
as much of the disk as you want.  It is NOT necessary to allocate the entire
disk.  Set the physical size of the partition such that the physical starting
block + the size do not exceed the physical size of the disk.  Set the logical
start to 0, and the logical size the same as the physical size.  Since you
will not have a Swap partition on the disk, set Root=no, Usr=yes.  I have
found it helpful to do a 'badblk' on the partition before doing the 'mkfs'.
Be sure to do a 'fsck' on the new file system, as mkfs always leaves the last
block unlinked, for some reason.

The mkfs command takes its parameters in 512-byte blocks, but reports the
file system in 1024 byte logical blocks.

Marc Kaufman (kaufman at polya.stanford.edu)