Stands for "Logical Unit Number." LUNs are used to identify SCSI devices, such as external hard drives, connected to a computer. Each device is assigned a LUN, from 0 to 7, which serves as the device's unique address.
LUNs can also be used for identifying virtual hard disk partitions, which are used in RAID configurations. For example, a single hard drive may be partitioned into multiple volumes. Each volume can then be assigned a unique LUN. However, few modern computers use LUNs, since SCSI devices have mostly been replaced by USB and Firewire devices.
This page contains a technical definition of LUN. It explains in computing terminology what LUN means and is one of many technical terms in the TechTerms dictionary.
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