ATTO Technology 2200R/D, 3200R Virtual Device Addressing Method, Logical Unit Addressing Method

ATTO Technology, Inc. ATTO FibreBridge Installation & Operation Manual

parameter allows the host to specify that the peripheral device addressing method will be used regardless of the Addressing Method field in the first level address. This allows custom address translations to be built for systems that may not properly support hierarchical addressing.

Virtual Device Addressing Method

Bit Number

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1							LUN

The LUN field indicates the address of the device to which the command will be routed. The FibreBridge will extract the Bus Number, Target and LUN fields from the LUN based upon parameters contained in FibreBridge non-volatile RAM. The default configuration imposes the following definitions on the LUN field. The SAM-2 specification leaves this to be too arbitrary so again, the FibreBridge default settings are as listed below.

Bit Number

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	1			N/A				LUN			Target			Bus Identifier

Again, the location and width of the Bus, Target and LUN fields are field programmable and are stored in FibreBridge non-volatile RAM. This allows custom address translations to be created to meet special requirements for the customer, operating system, host bus adapter or peripheral device.

Logical Unit Addressing Method

Bit Number

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	0			Target				Bus Number					LUN

The Logical unit address method behaves exactly as the Peripheral device address method with two notable exceptions – field placement and width. The Bus number and Target fields have been moved. The LUN and Target fields are larger and the Bus number field is smaller. The FibreBridge will decode logical unit addressing as described in the peripheral device address method section. Just as with the peripheral and virtual modes, the location and width of the Bus, Target and LUN fields are field programmable. The default mode for Logical Addressing is the same as defined in the SAM-2 specification.

FibreBridge Default Mode

By default, the FibreBridge suppresses the above methods of Hierarchical Addressing and uses its own method, which closely follows the rules of peripheral addressing. This method of addressing is in effect regardless of the Address Method field in the first level address unless you select the option to perform LUN translations.

Bit Number

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	0			N/A					LUN			Target			Bus

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