Could someone from NetApp provide more detail here? I'm sure you can move from one point to another over NFS, but if you are working from /, you can't do an NFS rename call from one tree to another?
Nope.
Quota trees are best thought of as "virtual partitions". (In fact, I think that's what Dave had in mind when he first put them in.) Attempts to move stuff into or out of them gets EXDEV, and, in sufficiently recent releases (I think I fixed this in 3.0 or 3.1 or so):
*IF* you've mounted the root of a quota tree from a client (because many clients, including Sun's, do not, on a "statfs()"/"statvfs()"/"ustat()"/etc. call, send a file handle for the argument to the call to the server, they send a file handle for the mount point), you get the space free in the quota tree (minimum of space left in the file system and in the quota);
if you exceed the quota, you get ENOSPC, not EDQUOT.
Unlike real partitions, you can increase or decrease the size relatively easily, by adjusting the quota ("relatively", given that adjusting quotas can be a pain).
What happens when you try to use mv?
"mv" tries a "rename()" (unless it's a crufty old version of UNIX, in which case it tries a "link()", with an "unlink()" to follow, but the results should be the same), gets an EXDEV error, and says "oops, they're on different file systems", copies the file to the destination, and removes the source.
What can't you do from a NFS/SMB client point of view?
Move files into or out of the quota tree.