Sorry, this was almost two years ago. I don't remember the details. But from going through the posts, I'd say that I just replaced the disk and did not issue the repair command.
I had this problem once as well and I was looking for a way to avoid running into it again.
Someone pointed out that you can set a quota on a zpool to protect some space from being used.
zfs get quota <poolname>
Unfortunately, this gives you...