What is a Logical Unit Number (LUN)?

What does LUN stand for?

A logical uNit Variety (LUN) is a Range of used for figuring out a logical unit referring to Laptop Storage. A logical unit is a tool addressed by way of Protocols and related to Fiber Channel, small laptop Device Interface (SCSI), Internet SCSI (iSCSI) and other comparable interfaces.

LUNs are essential for dealing with the Block garage Arrays of a garage location Network (SAN). A normal LUN is used with any aspect assisting examine/write Methods. LUNs are commonly used for logical discs produced on a SAN.

The term LUN turned into initiated from the SCSI protocol and provided a technique for identifying unique disC Drives inside a normal element inclusive of a disc array. Frequently, the time period LUN is used in connection with the real disc pressure, which isn't technically correct. Additionally, a LUN may also talk to an Input/Output (I/O) Access channel within decided on Programming Languages. Today, LUNs are found now not handiest on disc drives, however also on virtual Partitions or on Volumes of redundant arrays of independent disks (RAID) the use of multiple drives.

What Does Logical Unit Number Mean?

A fashionable disc array has numerous SCSI ports. Each SCSI port has an assigned target cope with. The disc array is Formatted as RAID and partitioned into diverse Storage Devices. Each extent is configured with a logical unit. There may be severa logical units Characterizing numerous volumes. Likewise, a disc power with a single SCSI port usually has one goal with a novel logical unit with a 0 LUN. The zero indicates the whole garage of the disc force.

Each device is given an exclusive quantity among 0 and 7 for an 8-Bit Bus or a range of among 8 and 16 for a sixteen-bit bus. A tool initiating an I/O Request is an initiator. A tool executing the request is the target. An character target has the ability to Interconnect with up to 8 or more Components using one Controller. These components are the logical devices.

An SCSI LUN may be addressed with a aggregate of the conTroller ID, the goal ID, a disk ID, and on occasion the slice ID. The identifications (IDs) in a Unix OS are commonly Joined as one word. A normal Instance is the cope with c1t2d3s4. This refers to controller 1, goal 2, disk 3 and slice 4. Full tool addresses are as follows:

• c-element: controller ID of Host Bus Adapter
• t-part: target ID Classifying SCSI goal on the bus
• d-component: disk ID classifying LUN on the target
• s-element: slice ID classifying actual slice at the disk