From: rhealey@rogue.digibd.com (Rob Healey)
Subject: Re: 'Proper' filesystem distribution
Organization: DigiBoard Inc., Eden Prairie, MN
Date: Mon, 25 Jan 1993 17:43:49 GMT

In article <Bradb.0oco@nesbbx.rain.COM>, Bradb@nesbbx.rain.COM (**) writes:
|> (I wanted to follow-up to something rhealey@rogue.digibd.com (Rob Healey)
|> said about Amiga Unix not liking / and /usr on seperate file sytems but I
|> can't seem to find the article so here goes...)
|>  
	Gee, that's me!! B^).

|> What is the 'proper' distribution of filesystems assuming that you have
|> several drives, each of (approximately) the same access times?
|>  
	Religeous issue actually and normally involves an iterative process
	as you figure out the dynamics of your particular setup. You can
	make generalizations, and the 4.2 UNIX manuals that come with UNIXware
	do give some good pointers in this dept, but in general you have to
	take some data and analyze where your drives are spending the most time
	and put the popular stuff there.

|> I've got a 300MB and 2 150MB drives and I'm wondering how I should split
|> out the file systems to get the best performance.  (I'm getting a 600MB
|> disk from work for Usenet and to keep sources on, so I'm just thinking
|> about the basic stuff on the other drives...)
|>  
|> Unix people at work suggested the following distribution:
|>  
|> 150MB  /
|> 150MB  /usr
|> 300MB  /home
|>  
	The UNIX people at work don't have AmigaUNIX... The / and /usr
	dependancy is due to some AmigaUNIX setup dependancys that
	assume / and /usr are on the same slice so hard links and
	other things work. If you break up / and /usr on AmigaUNIX I
	believe the startup scripts/programs will break. I've never had
	the time to putts with this and since I can use ufs, and thus
	don't have to worry about 65500 inodes/slice limits, I can keep
	both on the same slice.

|> Any comments?  Is this bad?  Good?  (Also recommended to have a swap
|> partition on *each* drive equal to the amount of 'real' memory)
|>  
	Hmm, I'd say 1 swap partition twice the physical memory size should
	be enough on most SVR4 based systems. SVR4 is a little better with
	memory that BSD or SVR3.2 so twice physical on 1 slice should be
	enough. You can add a paging file via the swap command if you
	ever need it but I doubt you will. The one case I've seen problems
	with is compiling gdb 4.7, for that I had to set my memory limits
	from 16M/process to unlimited so the damn thing would link! Luckily
	32M of paging area did the trick and it was just a ulimit problem.

|> Is it possible (and desirable?) to have multiple swap partitions, each on
|> seperate drives?
|>  
	Swap on a drive not containing active file systems MIGHT be a good
	idea but it's a bear to get right under AmigaUNIX due to the way
	you have to compile the kernel. The other issue is that those other
	people are probably giving you advice based on SunOS, BSD or SVR3.2
	experience which isn't always accurate for SVR4. Especially in the
	paging dept, what's good for SunOS,BSD or SVR3.2 might prove overkill
	for SVR4. SVR4 pages text area from the executable image on the
	file system and data areas are shared copy on write. Additionally
	ALOT of code is in dynamic librarys that don't touch the paging area
	either. So, SVR4 tends to use alot less paging area than the other
	OS's.
	( A note for you pedantics out there, yes I know I've over simplified
	  the explaination of SVR4 VM...)

	Since AmigaUNIX has other efficiancy problems, it was never tuned, I
	would say stick with the stock setup slices and put user file
	systems on the second drive leaving /,/usr and paging on the first.

	By the way, has anybody tried tuning the variables in kernel.h? While
	looking over the UNIX 4.2 manuals that come with Univel I noticed that
	a 16M machine should have BUFHWM set to 1024, AmigaUNIX had 200. This
	supposedly sets an upper bound on the number of disk block buffers
	the kernel can alloc(). I up'd it on kas and it seems to have
	improved disk performance a bit on compiles. Has anybody found any
	other tuneables worth tuning?

	I wish somebody would do a 4.2 port to the Amiga, the new X based
	debugger, X application building and other tools are making my
	mouth water... Oh well, I guess I'll have to play with 4.2 at the
	office instead...

		-Rob
Newsgroups: comp.unix.amiga