Subject: Re: default /usr partition
To: David Brownlee <>
From: Gandhi woulda smacked you <>
List: tech-install
Date: 08/16/1999 20:13:51
On Mon, 16 Aug 1999, David Brownlee wrote:

# On Tue, 17 Aug 1999, Simon Burge wrote:
# > >         The current letters used for /usr in sysinst are:
# > > 
# > >             D: alpha pmax vax x68k
# > >             E: arm32 bebox i386 pc532
# > >             G: macppc sparc
# > >             ?: mac68k (uses MacOS partitions - may be 'G')
# > > 
# > >         It would be nice if we could try to move towards some recommended
# > >         value where possible. Since sysinst currently either leaves
# > >         everything alone (upgrade) or blows everything away and starts
# > > 	from scratch (install), it shouldn't be _too_ disruptive.
# > 
# > I used to prefer "G" for /usr, since that's how our older BSDish boxes
# > used to get set up, but now I install all my NetBSD boxes with a large
# > root filesystem and no /usr (as I seen a few people suggest around
# > here).  Is there no reason why we shouldn't push in that direction?
# > 
# 	I'm definitely in favour of pushing for a default 'root + swap'
# 	only install, with easy option for /var and /usr, but that is
# 	an orthogonal issue :)
# 	ccing port-sparc as I'd like to start there.
# 	How unhappy would people be if I changed the sparc sysinst to
# 	default to using 'd' for /usr?

History as I understand it:

long story;

	'a' was made the root partition because it sat at the start of the
	disk and the filesystem code knew to look past the disklabel
	somehow.  Swap was NEVER put on 'a' because the swap code did NOT
	know how to look past the disklabel (these are semantics which, I
	presume, have been superceded by smarts in the driver which know
	where the disklabel starts).  Either that or the boot code didn't
	know how to look past fs block 0 for some silly reason...

	...and /usr wasn't put on root due to only using a small
	filesystem etc. blah blah woof woof and other reasons that, "given
	today's disk sizes and speeds", I'm sure Greg Woods and a few
	others would argue are moot.

	'b' was made the swap partition because it was the first partition
	available which wouldn't tromp on the disklabel when swapped upon.

	'c' was the entire disk, presumably because it was the first non-
	critical letter in use (you have root and swap, what else do you
	need for single-user mode).

	'g' was the next primary partition, and was usually of considerable
	size.  /usr went here, for the most part.

	'd', 'e', and 'f' were a triple which resided in the space usually
	reserved for 'g'; occasionally there was a 'd' which was subsumed
	by 'e' and 'f' as the disks got a little bigger.  'd' was usually
	used for /tmp if it wasn't a) on root or b) on another 'a' or
	'g'(!)  partition somewhere

	'h' was almost always bigger than 'g' if it could be.  Somehow
	'h' got adopted for /home directories, and they got moved out
	of /usr (which, to me, in this day and age, is a sound idea).

	You almost never saw <ctlr><unit>g and any of <ctlr><unit>{d,e,f}
	on the same disk.

	Later, as disk labels became a bit more dynamic (read: not compiled
	in to the kernel (Erik Fair can probably vouch for this one on the
	VAX Berkeley Distribution; and Pyramid OSx did this up to and
	including version 10(?)), and System V did this all the way up to
	and including SVR2, IIRC), it became easier to manipulate the way
	a disk was laid out.  Defaults were still suggested.  People tended
	to use 'a', 'b', and 'g' for root, swap and /usr.  Some people decided
	that they would even put root and /usr on separate spindles or even
	separate _controllers_ if possible because it would reduce the
	contention at the controller level, giving greater throughput.
	[here, again, I'm sure Greg would be happy to provide his thoughts
	on the matter if we felt like beating back an undead horse]

	Then the white paper on 4.4 BSD was written, and while 4.4 was in
	development, SunOS incorporated /var.  This began to reside on 'd'
	partitions (well, it did where I went, and this was before I was a
	full- fledged, Systems Administrator).

	And then came SVR4laris, and they created YAFS called /opt and
	plopped it on to the 'd' partition and moved /var to 'e'.  Of
	course, Solaris gratuitously then decided that /usr/openwin might
	need its own filesystem and offered to infect 'f' with

	And so there was a full disk.

(short) story = 1;

	I certainly wouldn't be unhappy, although given past paradigm
	I would admit to being a bit puzzled.  If it makes life any
	easier in the rest of the world, so much the better.

# 		David/absolute
#            -=-  "If there is a hell... I'll see you there"  -=-

Wow.  They force you to use NT at work, too?

NetBSD: We Stay Up.