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From: rbj@icst-cmr.arpa (Root Boy Jim)
Newsgroups: net.unix-wizards
Subject: Re:  RAxx disk partitons
Message-ID: <4757@brl-smoke.ARPA>
Date: Mon, 20-Oct-86 15:06:23 EDT
Article-I.D.: brl-smok.4757
Posted: Mon Oct 20 15:06:23 1986
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	Once again, I am compelled to ponder the rationale behind the choice
	of partition sizes for RA disks ( in particular, those for ra81's in
	4.3 ). It appears that the partitions begin on cylinder boundries, but
	end short of cylinder boundries, resulting in chunks of unused sectors
	between the partitons. Can anyone out there educate me on the purpose
	of this game of "musical sectors", or have I been living in the 
	outback of Neptune a little too long?
	
It's not only the RA81's. Long ago someone made up tables that were exact
cylinder multiples of some ancient disk, I think it was rp0[4567]'s.

Anyway, I find the defaults pretty bogus and have radically altered the
layouts by editing (and adb'ing) the tables in the driver. Our system has
two DEC rm03's with 50M `a' partitions containing root and user (so I can
use almost anything in /usr in single user mode), and the standard 33440
sectors (17M) used for swap at the end of the disk. For compatibility,
the `g' partition is as it was, the `d' partition looks like the old `a'.

On our rm05, the `d', `e', and `f' split the `h' partition, not `g'.

I won't even mention what we did to our eagle.

To get back to your question, however, it is safe to round up your
partition sizes to even cylinder boundarys, *** except for the last
partition on the disk ***. You must reserve at least two tracks for bad
block info, and I just avoided the last cylinder entirely.

	(Root Boy) Jim Cottrell		<rbj@icst-cmr.arpa>
	Yow!  It's a hole all the way to downtown Burbank!