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From: kempff@hppad.HP.COM (John Kempff)
Newsgroups: comp.os.minix
Subject: Re: PC HD partition boundaries for Minix
Message-ID: <2210002@hppad.HP.COM>
Date: 7 May 90 18:35:11 GMT
References: <380@trux.UUCP>
Organization: HP Panacom Automation Div Waterloo, Ont.
Lines: 33

> / hppad:comp.os.minix / car@trux.UUCP (Chris Rende) /  8:48 am  Apr 28, 1990 /
> I'm going to be partitioning a disk for Minix soon. I remember some discussion
> recently about partition boundaries starting on odd or even cylinders...
> but I can't remember exactly what it was about: could someone summarize any
> guidelines/warnings for partitioning a HD for PC Minix?
> 
I just finished installing MINIX 1.3 on my RLL hard disk.  I created
a DOS partition, MINIX /dev/hd3 for booting, and MINIX /usr partition.

My understanding was, that all partitions MUST have even number of sectors.
You can ensure this by using even number of cylinders per partition.  The
even number of sectors is required because MINIX file blocks are 1024 bytes,
but disk sectors are 512 bytes.  Minix only allocates blocks from your disk to
store files, not sectors.

One other cautionary note on partitions.  The order of partition entries
in the partition table on disk, does not necessarily correspond to the
the disk dev numbers.  The wini.c driver and fsck.c, when compiled 
standalone for use with the boot floppy, both sort the partition
table after they are read in.  Look at the end of these source files
for the code that does it.  The sorting is done by a local routine
sort().  I disable this code to make my life easier, thus /dev/hd1
is partition 1, /dev/hd2 is partition 2, etc. as shown by MINIX's fdisk.
DOS fdisk program also sorts the partition table beforing displaying them.

I've been running my system this way for about a month, both DOS and MINIX
on the same physical disk, with out any problems.

-----
John Kempff
Waterloo, Ontario, Canada

kempff@hppad.hp.com