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LUN masking

LUN masking definition

LUN masking is a process used in SAN (storage area network) environments to make a LUN (logical unit number) available to some hosts (servers connected to the SAN) and unavailable to others. A LUN is a unique identifier that designates individual devices or their groups in the SAN for data access.

The primary goal of LUN masking is to provide a layer of security and access control in a SAN environment. It prevents unauthorized hosts from accessing storage devices they shouldn't have access to, which can protect sensitive data and prevent accidental overwrites or corruption of data.

Here's a simple way to understand it:

Consider the SAN as a large storage unit filled with many smaller lockers (LUNs). Different people (servers) need access to different lockers. LUN masking is like giving out the keys (access) to the correct people for the right lockers.

See also: storage area network server, access management, unauthorized access, online data storage, shared storage

How LUN masking works

  1. 1.LUN identification. Every storage device in a SAN is assigned a logical unit number (LUN). This LUN acts like an address that allows the host to identify and communicate with that storage device.
  2. 2.Masking setup. In the SAN management software or hardware, the administrator sets up LUN masking rules. These rules define which LUNs are visible and accessible to which hosts.
  3. 3.Rule enforcement. When a host sends a request to access a LUN, the SAN checks the LUN masking rules. If the rules allow the host to access the requested LUN, the SAN grants access. If the rules don't allow access, the SAN denies the request.
  4. 4.Host view. On the host side, it can only 'see' the LUNs that the masking rules allow it to see. Any LUNs that are masked (hidden) from the host will be invisible as far as the host is concerned.

LUN masking benefits

  • Security. Only allowing specific hosts to access a LUN prevents unauthorized access, securing the data on that LUN.
  • Performance. LUN masking can prevent the overloading of a server with too many active connections that it doesn't actually need, thus enhancing performance.
  • Data integrity. LUN masking can prevent accidental overwriting or modification of data, as a server cannot modify data on a LUN it cannot access.
  • Control. LUN masking provides more granular control over the storage environment.