How to Get SCSI Drives to Boot

Investing in SCSI drives and peripherals can yield some fantastic performance, but only when set up properly. When you boot your PC from a SCSI drive, you need to be sure that everything is properly configured. This can be accomplished through following these steps.

Things You'll Need

• SCSI host adapter add-in card (if necessary)
• SCSI data cable (compatible with both host adapter and hard disk)
• SCSI hard disk (supported by host adapter)

Instructions

Hardware Configuration

1. Keep other SCSI devices disconnected until the boot drive is installed and working.
   For this procedure, keep the hard disk as the only device on the host adapter.

2. Check the SCSI host adapter against the SCSI hard disk for compatibility. There are at least eight different SCSI standards and seven different types of connectors used by SCSI devices. When you're certain that the host adapter is fully compatible with the hard disk, continue to the next step.

3. Connect the host adapter to one end of the cable. Most SCSI connectors have a protruding "key" or an asymmetrical design that makes an improper connection impossible. If the cable or connector is not designed this way, make sure to line up the red stripe on the cable to "Pin 1" on the connector.

4. Attach the SCSI hard disk to the SCSI data cable, ideally at the farthest end from the host adapter. This may seem awkward, however, it is best to use the entire length of cable so that the high-precision electronics do not "leak" electrical currents through disconnected wires.

5. Check to see if the hard disk is "self-terminated" and make sure that feature is enabled. If the drive is not self-terminated, move it to the next connector and put a compatible "active terminator" at the very end of the SCSI data cable. The terminator also prevents "leaking" of electric currents.

6. Connect power-supply cables to the hard disk and (if necessary) the host adapter as well. Once all devices are connected, continue to the next section.

Firmware Configurtaion

1. Power-on the PC and watch the screen for the SCSI setup prompt. This may appear right after the BIOS screen, asking you to press a specific key (for instance, F11 or Esc). If the SCSI host adapter is built-in on the motherboard, consult the motherboard documentation on how to trigger SCSI setup.

2. Watch the SCSI setup screen to see when the hard disk activates. Most host adapters will show active devices immediately. On the screen, you should see a description (such as the model number) of the hard disk you just connected.

3. Enable the hard disk as a boot drive. This can be worded in different ways, depending on the exact host adapter and/or BIOS extension you have installed. Most Adaptec® host adapters show an option for "Boot Target" that must be set to device 0 (zero). The LUN for the device should be set to the default, usually 0 (zero).

4. Enable "BIOS (Int 13h support)," which must be enabled when booting from a SCSI hard disk. It also prevents the PC BIOS from accidentally booting from other devices, like IDE or SATA disks. This setting is for Adaptec host adapters, however, the wording on your screen may be different (may also appear as "Int 0x13").

5. Use defaults on the remaining settings to boot from the hard disk. In some cases, check with the documentation or support website for the SCSI host adapter (not the maker of the hard disk). Verify that the physical settings (jumpers) on the hard disk itself are a match for these host adapter settings.

Tips & Warnings

• If you need additional troubleshooting, check the host adapter documentation.

• The proper order for SCSI disk preparation is: [1] Low-level format [2] Partitioning [3] Format partition volume(s)

• When in doubt, go out and purchase a new SCSI data cable. It's the least-expensive fix for most common problems.

• Newer host adapters support a mode called LVD, but when older (SE) devices are attached the host adapter may operate in SE-compatibility mode.

• Power off the PC while working on the internal components, but keep it plugged in and grounded to best handle electrostatic discharges.

• Keep the host adapter driver-disk handy when installing a new operating system; the host adapter may not function properly until the drivers are loaded.

• This article does NOT address any concerns with SCSI RAID systems; consult an expert and/or the documentation of the RAID equipment for troubleshooting.

• A low-level format on a SCSI hard disk erases ALL data; the hard disk will not boot until an operating system is installed.

• As with all delicate electronics, be aware of electrostatic discharges and keep yourself properly grounded when handling internal devices.

References

• Microsoft: Random Problems Encountered When Mixing SE and LVD SCSI Standards
• RAM Electronics: SCSI Standards and Cables for The Normal Person
• DataPro: All About SCSI