Can't figure out what's taking up space on /

grits# df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/sd0a 986M 936M 162K 100% /
/dev/sd0k 57.7G 23.7G 31.1G 43% /home
/dev/sd0d 3.9G 10.0K 3.7G 0% /tmp
/dev/sd0f 5.8G 1.1G 4.4G 21% /usr
/dev/sd0g 986M 234M 702M 25% /usr/X11R6
/dev/sd0h 16.8G 35.5M 15.9G 0% /usr/local
/dev/sd0j 5.8G 2.0K 5.5G 0% /usr/obj
/dev/sd0i 1.9G 2.0K 1.8G 0% /usr/src
/dev/sd0e 13.8G 18.8M 13.1G 0% /var
/dev/sd1c 440G 305G 113G 73% /backup

grits# du -xsh /
186M /

I just removed /bsd.sp to free up a little bit of space but I don't
understand the discrepancy between df and du. How do I troubleshoot
further?

Thanks,
Greg