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ATTO Technology, Inc.
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14
13
12
0
0
The RAID Group at SCSI LUN 2 will now be mapped as follows:
LLLL = 0010
LUN Byte: LLLL TTTB à 0010 0000 = Fibre Channel LUN 32
à RAID group will be detected at ID 3 LUN 32
Configuration for Consecutive IDs
The Default Addressing mode of the FibreBridge is ideal when you wish to connect SCSI hard drives and
for most SCSI tape drive configurations. Problems may arise with some tape or CD Jukebox application
programs that require consecutive IDs for the devices connected to a SCSI bus. The Default Addressing
mode also poses a problem with SCSI RAID Controllers.
These limitations are easily overcome because you can program the addressing mode in the FibreBridge.
The reason for putting the Bus Identifier bit in position 0 is to improve performance through the
FibreBridge. In the SCSI world, device ID 0 has the highest priority, followed by ID 1, 2, and so on. By
having even IDs on Bus 1 and Odd IDs on Bus 2, the priorities are balanced between the two busses.
If you need to design for consecutive IDs on the SCSI bus, simply move the bit position of the SCSI Bus
Identifier.
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0
0
For FibreBridge SCSI channel 1:
Translated LUN as it appears to the Host
For FibreBridge SCSI channel 2:
Translated LUN as it appears to the Host
Configurations for RAID Controllers
If you need to design for RAID Controllers with multiple LUNs, simply move the bit position of the SCSI
LUN Identifier.
Bit Number
11
10
9
8
N/A
TTT = 000
B = 0
Bit Number
11
10
9
8
N/A
SCSI Device ID
SCSI Device ID
ATTO Technology, Inc.
ATTO FibreBridge Installation & Operation Manual
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LUN
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6
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4
LUN
0 1 2 3
0 1 2 3
0 1 2 3
4 5 6 7
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3
2
1
0
Target
Bus
3
2
1
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Bus
Target
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