gauge zfs_space_avail           by name
gauge zfs_space_used            by name
gauge zfs_space_used_snap       by name
gauge zfs_space_used_ds         by name
gauge zfs_space_used_ref_reserv by name
gauge zfs_space_used_child      by name

# output of `zfs list -Hp -o space`
/(?P<name>\S+)\s+(?P<f0>\d+)\s+(?P<f1>\d+)\s+(?P<f2>\d+)\s+(?P<f3>\d+)\s+(?P<f4>\d+)\s+(?P<f5>\d+)/ {
    zfs_space_avail[$name] = $f0
    zfs_space_used[$name] = $f1
    zfs_space_used_snap[$name] = $f2
    zfs_space_used_ds[$name] = $f3
    zfs_space_used_ref_reserv[$name] = $f4
    zfs_space_used_child[$name] = $f5
}