In computer storage, a logical unit number, or LUN, is a number used to identify a logical unit, which is a device addressed by the SCSI protocol or protocols which encapsulate SCSI, such as Fibre Channel or iSCSI. A LUN may be used with any device which supports read/write operations, such as a tape drive, but is most often used to refer to a logical disk as created on a SAN. Though not technically correct, the term "LUN" is often also used to refer to the logical disk itself.
To add a lun, you can use either device manager or storage navigator. While storage navigator or element manager procedures might differ from array type to array type, device manager has the characteristic that the procedure to carve a lun is the same regardless of the array (HUS, VSP, USP) utilized. Please keep in mind that this article covers the procedure of allocating the space - operation also known as carving - only; don't assume that at the end the host will be able to see the disk.
Allocate disk to hosts
The workflow would be something like this
- Storage Request - System Administrator will request a disk of a specific size and performance requirement
- Zoning - SAN Admins (sometimes the same admins as the Storage Admins) will create logical connecting using FC or FCOE switches between the server's WWN and the array's target ports.
- Host registration - Storage Admin define the host into HDVM and specify the WWN's that belong to that host or use the HDVM agent to perform automatic registration
- Carving - Storage Administrator will carve the requested lun from a specific pool that will satisfy the performance requirements
- Mapping/Masking (allocation)- Storage Administrator will present the lun to a specific set of WWN pertaining to the host and which is zoned to specific Target ports
- Storage Discovery - System Administrator will rescan his host and add the new luns to the OS