A scan checks the block layout of a LUN, file, or volume before reallocating blocks. If the current layout is below the threshold, the scan does not reallocate blocks in the LUN, file, or volume. If the current layout is equal to or above the threshold, the scan reallocates blocks in the LUN, file, or volume.
Note: Because Data ONTAP also includes “hot spots” in its calculation of whether to start a LUN, file, or volume reallocation, the system might start a reallocation when the average optimization is better than the threshold but a small percentage of the total data is very poorly optimized.