ZFS lockup in "zfs" state

[Martin Matuska]

  Hi,

I just experienced the same lockup in zfs state as other people did 
(Ivan Voras, Peter Schuller) - UFS filesystems still intact.
There was heavy backup tar/gzip activity on the filesystem (read-only, 
write was to NFS) and lots of reads via NFS, the server was doing this 
job without problems for 11 days.

FreeBSD: 7-STABLE 2008-04-29
ARCH: amd64
RAM: 6 GB
ZFS: prefetch disabled
vm.kmem_size_max="1073741824"