Glossary 73
LED Light emitting diode.
local disk A disk in the host.
LU Logical unit.
LUN Logical unit number. A LUN results from mapping a SCSI logical unit 
number, port ID, and LDEV ID to a RAID group. The size of the LUN is 
determined by the emulation mode of the LDEV, and the number of 
LDEVs associated with the LUN. For example, a LUN associated with two 
OPEN-3 LDEVs has a size of 4,693 MB.
LUSE Logical unit size expansion. See also Expanded LUN.
m Meters.
MB Megabytes.
MCU Main control unit.
MIX A circuit board in the disk control unit that includes disk adapters and 
channel adapters for interfacing disk drives and the host to cache memory. 
mirroring 
consistency
The consistency (usability) of data in a volume (for example, S-VOL).
mm Millimeters.
MR Magnetoresistive.
ms, msec Milliseconds.
mutual hot standby 
system
Two servers that are poised to cover for each other if necessary.
NAS Network attached storage.
node Logically speaking, an environment where instances can be executed. 
Physically, a processor, which is an element of a cluster system.
NVS Nonvolatile storage.
OFC Open Fibre Control.
OLM Optical link module.