ATTO Technology, Inc.ATTO FibreBridge Installation & Operation Manual
Bit Number
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 |
| 5 | 4 | 3 | 2 | 1 | 0 |
0 | 0 |
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| N/A |
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| LUN |
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| Target |
| Bus | ||
The RAID Group at SCSI LUN 2 will now be mapped as follows:
LLLL = 0010 TTT = 000 B = 0
LUN Byte: LLLL TTTB à 0010 0000 = Fibre Channel LUN 32
àRAID 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.
Bit Number
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 |
| 6 |
|
| 5 | 4 | 3 | 2 | 1 | 0 |
0 | 0 |
|
| N/A |
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| LUN |
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| Bus | Target | |||
For FibreBridge SCSI channel 1: | SCSI Device ID |
| 0 | 1 | 2 | 3 |
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| Translated LUN as it appears to the Host |
| 0 | 1 | 2 | 3 |
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For FibreBridge SCSI channel 2: | SCSI Device ID |
| 0 | 1 | 2 | 3 |
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| Translated LUN as it appears to the Host |
| 4 | 5 | 6 | 7 |
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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.
ATTO Technology, Inc.
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