Limit to number of file structures... ?

[Chris Torek]

There is a hard coded limit on the number of *partitions* (usually 8,
/dev/foo0a through /dev/foo0h).  There's nothing that says you have to
make a file system use all of a partition, but you'd need a strange
driver (like Sun's network disk) that let you "indirect" into the
subpartitions.

In other words, suppose instead of using newfs or mkfs the way the
manual tells you, you do this:

First, figure out how much space you've got (let's say 400M).  Say
it's divided like this:

	a -  15M
	b -  15M
	c - 400M	(includes a, b, and g)
	g - 370M

Now suppose you make "a" a normal file system (for /) and "b" a normal
paging area.  Then instead of making "g" a 370M file system, you make
a file system at "g" that's only 185M.

Well, now there's 185M left at the end of the disk.  One problem remains:
you can't get to it.  (Well, strictly speaking, you can, by accessing
/dev/foo0g or /dev/rfoo0g and lseek()ing to 185M or more.)

Anyway, without some special hacks, that space is just gone.

If you don't have source, but are clever with adb, you can adjust the
sizes of your eight partitions however you like, but you're still stuck
with eight.  (Of course, with source, you can always go hack the driver
to support 16, or 75, or whatever you want.)

Also, you might note that there is a maximum number of mountable file
systems anyway (usually 15), so adding lots of partitions is probably
not a good idea anyway.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris at umcp-cs		ARPA:	chris at maryland