Noel Butler writes:

...

I found the same thing, and turning off write delegation seemed to have solved the problem. I still don't know why, though.

write delegation is disabled by default on NetApp with v4, or have they changed this now?

I think this is still the case: when I exported NFSv4, I also turned on both r/w delegation as well. The exported filesystem exhibited weird locking or slow write operations on NFS clients (e.g. "touch newfile" would take a second to complete). This went away when I turned off write delegation.

Joseph Tam <jtam.home@gmail.com>