Cannot umount /usr filesystem (ALWAYS "busy")

[joel m. cook]

For the past few weeks I have been unable to take the system into
single user mode (telinit s or telinit 1)
or even to shutdown without scragging /usr because when the attempt is made
by either the system or I to unmount it,
it's always "busy".  I have used telinit s
and then attempted to maually unmount it, but no luck.  Using ps to
see what's busy has been no use, and fuser reports no files in use
on /dev/dsk/1s3, which is the device/partition it's on.  I first noticed
the problem a few weeks ago after massive damage to the root filesystem
caused by bad memory-induced "PANIC's".  Now, I am  unable to unmount
/usr, which means that any shutdown results in fsck being invoked etc.
Any help will be much appreciated, e.g., is there a problem with /usr
being on the second disk (don't see why)? how can I find out (since
fuser gives no help) why umount thinks it's busy? 

Thanks for any pointers in the right direction!
-- 
			Joel M. Cook
			jmcook at jorel.apldmt.com
			"...20 years of schoolin' and
			 they put you on the day shift..."