The logical unit URI type describes fibre channel (FC) or serial-attached SCSI (SAS) storage devices. It refers to a logical unit (LU) based on its device ID (WWN). The logical unit storage URI always represents an entire disk.
The following is a list of URI syntax.
lu:luname.naa.ID
lu:initiator.naa.ID,target.naa.ID,luname.naa.ID
Examples of the use of the URI syntax are as follows:
lu:luname.naa.5000c5000288fa25
lu:initiator.naa.2100001d38089fb0,target.naa.2100001d38089fb0,luname.naa.5000c5000288fa25>
In the luname-only URI form, the ID describes a logical unit name.
In the initiator,target,luname form, an initiator specifies an initiator port and a target specifies a target port. Together, they specify a path to the logical unit. The logical unit name in the second syntax must match the URI's luname in the first syntax, the luname-only form.
It is best to use multipathing in conjunction with luname-only URIs. If multipathing is disabled and a luname-only URI is used, a random path to the specified logical unit will be chosen. To avoid random path assignment an initiator,target,luname URI form can be used to select a specific path to a logical unit. If multipathing is enabled and an initiator,target,luname URI form is used, then the multipathing framework controls which paths are used to access the logical unit, and the URI is only used to identify the unit, not the access path.