Single Ended and Differential SCSI Buses
The SCSI standard defines two electrical buses:
•a single ended bus
•
Maximum Cable Length for SCSI Standards
| Standard | Single ended | LVD | Maximum Number of |
|
|
|
|
| Drives |
|
| SCSI I | 6 m | 12 m | 7 |
|
| Fast SCSI | 6 m | 12 m | 7 |
|
| Fast Wide SCSI | 6 m | 12 m | 15 |
|
| Ultra SCSI | 1.5 m | 12 m | 7 |
|
| Ultra SCSI | 3 m | 12 m | 3 |
|
| Wide Ultra SCSI |
| 12 m | 15 |
|
| Wide Ultra SCSI | 1.5 m | 12 m | 7 |
|
| Wide Ultra SCSI | 3 m | 12 m | 3 |
|
| Ultra 2 SCSI |
| 25 m | 1 |
|
| Ultra 2 SCSI |
| 12 m | 7 |
|
| Wide Ultra 2 SCSI |
| 25 m | 1 |
|
| Wide Ultra 2 SCSI |
| 12 m | 15 |
|
| Ultra3 SCSI |
| 25m | 1 |
|
| Ultra3 SCSI |
| 12m | 7 |
|
| Wide Ultra3 SCSI |
| 25m | 1 |
|
| Wide Ultra3 SCSI |
| 12m | 15 |
|
|
|
|
|
|
|
SCSI Bus Widths and Maximum Throughput
| SCSI Standard | SCSI Bus Width | SCSI Throughput |
|
| SCSI I | 8 bits | 5 MB/s |
|
| Fast SCSI | 8 bits | 10 MB/s |
|
| Fast Wide SCSI | 16 bits | 20 MB/s |
|
| Ultra SCSI | 8 bits | 20 MB/s |
|
| Wide Ultra SCSI | 16 bits | 40 MB/s |
|
| Ultra 2 SCSI | 8 bits | 40 MB/s |
|
| Wide Ultra 2 SCSI | 16 bits | 80 MB/s |
|
| Ultra3 SCSI | 8 bits | 80 MB/s |
|
| Wide Ultra3 SCSI | 16 bits | 160 MB/s |
|
|
|
|
|
|
2MegaRAID Express 500 Hardware Guide