Report LUNS - A0h

The library will return a list of the logical units that it supports. When this command is sent to a controller device logical unit or tape drive hosting a media changer device logical unit, it will return a list of all additional logical units that are available. This list will primarily be media changer devices representing the configured Logical Libraries. When this command is sent to any of the media changer device logical units, they will only report themselves.

This command can be used to retrieve what Logical Unit Numbers are supported to avoid scanning for all possible numbers. It is useful for identifying the various Logical Libraries that may be configured.

The REPORT LUNS CDB format is shown in the following table.

Table 1: REPORT LUNS CDB format

Bit Byte	7	6	5	4	3	2	1	0
0	Op Code (A0h)
1	Reserved
2	Reserved
3	Reserved
4	Reserved
5	Reserved
6 : 9	Allocation Length
10	Reserved
11	Control

Field	Description
Allocation Length	This field must be set to a minimum of 10h (16 bytes) to retrieve information for at least a single LUN.

Table 2: Report LUNS Response

Bit Byte	7	6	5	4	3	2	1	0
0 : 3	LUN List Length (n-7)
4 : 7	Reserved
8 : 15	First LUN
n-7 : n	Last LUN

Field	Description
LUN List Length	This field returns the length in bytes of the list of LUNs being returned.
LUN	These fields return each available assigned LUN. The information conforms to the Logical Unit Address Method defined in SCC-2, and supports only First Level addressing (for each LUN, only the second byte is used and contains the assigned LUN).