Subject: Re: Why the partitioning should stay the same
To: Chris G Demetriou <Chris_G_Demetriou@LAGAVULIN.PDL.CS.CMU.EDU>
From: Andrew Cagney <>
List: tech-kern
Date: 01/31/1995 10:51:44
Excerpts from mail: 30-Jan-95 Re: Why the partitioning sh.. Chris G
Demetriou@LAGAVU (1122)

	[ I wrote ... ]
> > 	o	one file system
> > and	o	one swap swap area
> > 
> > within an existing DOS or MAC disk partition.

> except, you can do that already.

>> e.g. from a machine i've got an account on:

> % df
> Filesystem  512-blocks    Used   Avail Capacity  Mounted on
> /dev/sd0a       340870  296006   27820    91%    /
> /dev/sd0g      2909016 1021508 1742056    37%    /a
> % /usr/sbin/pstat -s
> Device      512-blocks     Used    Avail Capacity  Type
> /dev/sd0b       174296    66440   107856    38%    Interleaved

> and there's no reason to think that you _have_ to have a /a; i.e. it's
> there because the person who configured it wanted it to be.

> you don't even need a seperate sd0a vs sd0b, if you swap on to a vnd
> device in the file system.

Perhaphs this is what should be done as the default `simple'
installation (i.e. one file system, no swap space and swap to a file,
sick but simple ... :-).  With a unified VM/FS cache the overhead might
even be minimal.  If, however, the overhead was significant then I think
that swapping to a raw device would be a prefered choice.

> In other words, you can already do it, and to add _another_ way to do
> it adds no benefit and consumes space and effort.

(I suspect you know :-) The original reason for pointing this method out
came from the Mac groups discussion about their future partitioning
schema.  Briefly, the two choices were:

	a.	the PC solution of UNIX partitions within a native
		(DOS) partition.  Then some hybrid schema to get
		access to the other native partitions.

	b.	use the native partition directly

If option a. was chosen (I think that was your preference) then, ok, you
can carve up the dedicated partition the way you want.  If, however,
option b. was selected, then I believe that being able to more
efficiently use each partition (for instance combining FS and raw swap)
would be important.

So, if vn swapping was only marginaly slower or if the Mac group elected
to use partition option a. then my suggestion would be mute.  If,
however, they look to option b., and file swapping was significantly
slower, then I think the suggestion would be very useful.