The EMC Luns Layer
A LUN is a Logical Unit Number. It can be used to refer to an entire physical disk, or a subset of a larger physical disk or disk volume. The physical disk or disk volume could be an entire single disk drive, a partition (subset) of a single disk drive, or disk volume from a RAID controller comprising of multiple disk drives aggregated together for larger capacity and redundancy.
Isolate bound and unbound LUNs, overloaded LUNS and those that are experiencing errors using the test mapped to this layer.
Figure 1 : The test mapped to the EMC Luns layer