Getting ZFS per dataset IO statistics (or NFS per export IO statistics)
How about this... In this instance I have a ZFS filesystem '/volumes/lab3_pool_a/data02/alpha/' and I am using fsstat to get some basic statistics about it. Notice, I am getting stats for both, ZFS as a whole, and this one filesystem. By the way, fsstat has some good options and may give you just what you need.
# fsstat zfs /volumes/lab3_pool_a/data02/alpha/ 1
new name name attr attr lookup rddir read read write write
file remov chng get set ops ops ops bytes ops bytes
0 0 0 27 0 27 0 0 0 1 208 zfs
0 0 0 0 0 0 0 0 0 0 0 /volumes/lab3_pool_a/data02/alpha
Adding to slashdot's comments above: this one-liner does the same thing over all ZFS datasets (as determined by the pattern of the device column in mount(1M) output:
fsstat -i `mount | awk '{if($3 ~ /^[^\/:]+\//) {print $1;}}'` 1