I've been bit by 1549 as well, and had to run wack. One thing I've noticed, is that whenever I've had to run wack (too often), it finds about a bazillion things to fix. What I'd like to see is a version of wack that I can run from the console, when the filer is up, in a mode similar to "fsck -n". This way I could periodically check my filesystem's integrity, and perhaps schedule downtime, to run wack, before the corruption gets too great. Better yet would be that NetApp fix the problems that cause the corruption in the first place. Failing that though, I would prefer to know about corruption of my filesystem BEFORE I have a system crash.
-ste