File system limit in 4.2 BSD

[dhb at rayssd.UUCP]

Has anyone ever successfully gotten more than 15 file systems on a 4.2 BSD
system?  After many long delays, we are finally going to convert from 4.1
to 4.2, and we need to be able to mount more than 15 file systems.  I tried
making the same changes that I made in 4.1 (increase the size of mdev in the
cmap stucture, increase NMOUNT and NSWAPX in param.h, fix mount/umount) but
it doesn't seem to work.  I even talked to Mike Karrels in Dallas and he
indicated that that was all I had to do.  The problem we are experiencing
is that random processes dump core at random times.  This can be very
annoying if the shell core dumps, and it can be disastrous if "init" core
dumps.  The behaviour seems to indicate some kind of swapping error.  At
first I didn't even associate this problem with the changes to the coremap
structure but in a final act of desperation I backed off the change and
now the system runs fine.  We have been trying to track what we thought
was a weird swapping error for three months (tues and wed eve.) and have
now been running smoothly WITHOUT the coremap changes for over two weeks.
We now feel that all our other changes are done and the system is ready to
release to the users.  The only problem is that one of our machines
currently has eighteen mounted file systems and another one has
twenty-three!  To compound the problem, we are also expecting delivery
of six new disk drives (400M Eagles).  Before anyone says "Why dont you
just make a few bigger file systems?", there are internal political
reasons why we need to portion out the disk space in relatively small
(30 - 60 Meg) chunks.

Sorry for rambling on so much but if anyone has ever gotten more than
15 file systems to work, PLEASE let me know how you did it.
-- 
	Dave Brierley
	Raytheon Co.; Portsmouth RI; (401)-847-8000 x4073
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