How does a LUN relate to notation CxTxDxSx?

In a Unix environment, how does a LUN relate to the controller naming convention of CxTxDxSx?
While it can vary depending on Unix implementation, typically the notation CxTxDxSx refers to controller or channel path from the server (the HBA), target address of the device, device sub-address ( LUN) and, on some systems, the slice or partition on the disk. So, for example, C0T0D1S4 would represent the HBA identified with an address of 0, a SCSI target (even for Fibre Channel) of 0, LUN 1, and Unix slice or partition number 4. Note that a LUN or storage device that is multi-pathed could have multiple addresses pointing to the same LUN. If a server has two HBAs, one being C0 and the other being C1, and a LUN on a storage device that is accessible via a dual controller RAID array with SCSI targets T0 and T1, then the following addresses point to the same LUN: C0T0D1S4, C0T1D1S4, C1T0D1S4 and C1T1D1S4.
This was first published in September 2004

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