Technical Comparison
SCSI vs Fibre Channel - at a glance
| Ultra Wide SCSI | Fibre Channel | |
| Theoretical maximum throughput | 40 MB/s | 100 MB/s |
| Real-world maximum throughput | < 35 MB/s | > 95 MB/s |
| Clock rate | 20 MHz | 1062 MHz (= 1 GHz) |
| Data transfer format | Parallel: 16 bits | Serial: 1 bit |
| Cable type | Unwieldy: 68 wire copper | Simple: 4-wire copper or 2-core optical fiber |
| Maximum number of devices | Few: 16 per bus | Many: 126 per loop, 16 million on a switched fabric |
| Maximum distances |
Total bus length: Single-ended - 5 meters |
Between any device & hub or switch: Copper cable - 30 meters |
| Electrical noise susceptibility | High | Copper cable (coax) - Low Optical cable - None |
| Termination | Terminators required | Not required |
| "Re-cabling" - i.e. adding or removing a device | Downtime required: full bus power-down for safe re-cabling | Non-disruptive: can be done while the system is "hot" |
| Networking Topologies | None: point-to-point only | Loop/shared bandwidth (uses hubs) or switched fabric (uses switches) |
| Error detection features | Limited: 1 bit parity per word | 8/10 bit encoding with 2 bit disparity 32 bit CRC per frame Unique frame start & end sequences |
| Upgrade options | Ultra2 SCSI (80 MB/s) | 2 Gbps FC (200 MB/s) 4 Gbps FC (400 MB/s) |
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