When I set up my OES Linux server, I thought I had partitioned it the way I
wanted, but I now see it is different than I planned.

I have 72GB of RAID5 space. When I ran the install, I made a 25GB partition
for the root and I wanted to leave the other 47GB to make an NSS volume. I
must have missed a prompt somewhere because I now see I have no space left
and my 47GB partition is mounted as /usr

So, I figured I could just copy /usr to /usr2 ,umount /usr, and then rename
/usr2 to /usr. Then I could delete the old /usr partition and create an nss

Problem is, I get "file system busy" when I try to umount /usr

Two questions:
1. Is my method correct?
2. How do I get around the "file system busy" error?