Disk Options
Some of the input signals to a Fibre Channel disk are used to control options, as follows:
START options - if all the disks in an enclosure spin-up immediately on power-on, this can overload the power-supply. Two methods are available to avoid that problem:
| START1 | START2 | Spin-up behaviour |
| 0 | 0 | Automatic, immediate |
| 0 | 1 | Wait for Start Unit SCSI command |
| 1 | 0 | Staggered, delayed depending on loop address |
| 1 | 1 | Reserved |
DEVCTRL options - a disk that has the wrong interface speed can cause serious problems if it is inserted into an enclosure. That problem is avoided by providing three input pins to the disk that define the interface speed at which it will operate:
| DEVCTRLx value | Interface speed |
| 0-4 | Reserved |
| 5 | 4 GB/s |
| 6 | 2 GB/s |
| 7 | 1 GB/s |
Read more about this topic: Fibre Channel Electrical Interface
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