An iSCSI Logical Unit (LU) is a type of block storage that can be accessed by iSCSI initiators as a locally attached hard disk. An LU is stored as a file on the server file system. iSCSI LUs are bound in size using the server size management tools, including virtual volumes and quotas. LUs are created with a specific initial size but can be expanded over time, as demand requires.
A file must have an .iscsi extension to identify it as an iSCSI LU. However, apart from this extension there is no other way to determine that a file represents an LU.
After an LU is created and the iSCSI domain name is set, an iSCSI Target is created to allow access to the LU. A maximum of 32 LUs can be configured for each iSCSI Target. For more information on iSCSI Target, see iSCSI targets.