SCSI checklist

SCSI ID (device address jumper settings):
Each device must have a unique SCSI ID.
Recommended SCSI ID for the boot device is 0.

Interface type:
If you have more than one SCSI device on the cable, make sure that all devices are of the same type.
High Voltage Differential (HVD) SCSI devices are not compatible with Single Ended (standard) or Low Voltage Differential (LVD) SCSI devices.

Termination:
SCSI systems should have termination at both ends of the cable. Make sure that the controller terminates one end of the cable and that a drive supplies termination at the other end. If a drive doesn't have onboard termination, a terminator should be placed on the last connector of the cable.

Make sure that there is no extra cable after the terminator at the end.

Any device attached that is not at the end of the cable must have internal termination disabled.

For adapters with multiple SCSI ports with differing performance, ALL ports must be correctly terminated.

For adapters with a common port with both internal and external connections in use, DO NOT enable termination on the controller.

Narrow (50 pin) devices SHOULD NOT be connected at the end of a wide (68 pin) SCSI cable. A terminator in a 50 pin
SCSI device cannot provide the correct termination for the unused data lines.

Using a 68-50 pin cable converter to connect a 68 pin disk drive to a 50 pin SCSI adapter could cause problems because the 68-50 pin cable converter leaves 18 of the 68 pins on the disk drive without termination.

Resolution:

Place the 68 pin drive at the end of the bus and set the jumpers for the drive for active termination which provides termination to all 68 pins. If the drive does not provide termination, the converter should provide on board termination so that all unused lines are terminated.

The termination for a drive should match the interface type of drive. For example, Single Ended drives should use Single Ended terminators.

Cables and connectors:
Check that the cables are seated tightly and that no pins are bent.
If possible, try replacing the cable and terminators and use the drive's internal termination.
Make sure that pin 1 of the cable is plugged into pin 1 of the SCSI connector. Pin 1 on the SCSI cable is normally identified by a red or red-striped wire. This is especially important if you are using cables or connectors (on the SCSI adapter) that are not keyed. The connectors on our drives have a slotted key to prevent you from plugging the cable in backwards but not all SCSI cables are made with a key.

Ensure that the drive is jumpered to enable auto start when power is applied.

Try resetting the SCSI adapter defaults:
Enable "Reset IC Initialization"
Disable "plug and play" SCAM support
Enable "Unit Start" command
Enable Synchronous and Wide negotiations if available

Ensure that the drive is jumpered to disable sync negotiations.

Does the drive spin up and remain spinning?

Does the SCSI adapter recognize the drive during boot up?

Check that the cable lengths are within the ANSI specification for the interface transfer rate used and the number of devices installed on the bus.

If the drive is attached through a removable carrier, try removing the drive from the carrier and attaching the drive directly to the bus.

If you are using a narrow bus/cable (50 pin) with a wide (68 pin) device and a wide SCSI adapter, try disabling wide negotiation in the adapter settings.

LVD devices are backward compatible to Single Ended adapters as long as the system and the drives are configured correctly. When attaching LVD devices to Single Ended, Wide or Narrow adapters, the following applies:

LVD hard disk drives have no termination on the drive.

You must provide termination externally, either from another device or from a separate termination block.

Depending on how the adapter handles the "Diff Sense" line on the interface, you may need to set the jumper on the drive to Force Single Ended mode.

On multi-channel SCSI adapters, do not use more than two channels off each adapter.

In RAID environments, it is important to disable SCAM.

Disable at the adapter, if available.

Disable at the drive. This is only necessary with the DORS-3xxxx, DCAS-3xxxx and DDRS-3xxxx family of SCSI drives.
Newer drives have SCAM disabled as default or removed completely.