SCSI Drives

SCSI Drives

Some drives have a special design called small computer system interface, or SCSI. This design allows you to attach multiple drives to a single SCSI channel.


  1.  Any information about SCSI drives also applies to  other SCSI devices, such as tape drives.
  2.  If you plan to install both internal and external  SCSI devices, you must follow the instructions in 'External Options', in addition to  the instructions in this section.

A 16-bit (wide) SCSI cable connects the hot-swap backplane to one channel of the integrated RAID SCSI controller on the system board. An additional 16-bit SCSI cable with connectors for optional devices in bays A and B connects to the second channel of the RAID controller. This cable has a terminator at the other end and is folded and restrained with a cable clamp to the bottom of the server between the open bays and the power supply area.

SCSI IDs: Each SCSI device that is connected to an individual channel of the RAID controller needs a unique identification (ID) so that the controller can identify the devices and ensure that different devices do not attempt to transfer data at the same time. (The two channels of the integrated RAID controller operate independently.) If you need to set IDs for SCSI devices, refer to the instructions that come with those devices.

The server automatically sets SCSI IDs for hot-swap hard disk drives, according to the jumper settings on the SCSI backplanes. The server uses the hard disk drive SCSI IDs to send status information to the indicator lights above each hot-swap bay.

The SCSI backplane in the server supports up to six hot-swap bays. Table 8 shows the default SCSI IDs that the backplane assigns for hot-swap hard disk drives.

Automatically Assigned SCSI IDs 

      Bay  | 1 | 2 | 3 | 4 | 5 | 6
       ID  | 0 | 1 | 2 | 3 | 4 | 5

Note: The defaultSCSI ID for the SCSI backplane is 15. The default SCSI ID for each channel of the RAID controller is 7.

You can change the default ID addresses of the drives by changing the jumper settings on the SCSI backplane. See 'SCSI Backplane Option Jumpers'. A simplified layout of the SCSI backplane is shown in 'SCSI Backplane Component Locations'

The processing sequence for SCSI devices is set through the ServeRAID Configuration Utility program. The sequence proceeds from the lowest SCSI ID to the highest (0 to 6, then 8 to 15 determined by the jumper settings).

Termination (Internal SCSI Devices): SCSI buses must be terminated at each end. The ends of the SCSI buses in the server are already terminated.

All the hot-swap drives in the server have automatic termination and the RAID controller provides termination at the other end of the SCSI bus.

If you install SCSI devices in the removable-media bays (bays A and B), you must disable the termination on the devices, the RAID controller is already terminated and the SCSI cable for devices in the removable-media drive bays has a terminator at the other end. For example, when you install a SCSI device in a removable-media drive bay (bay A or B), set its termination to Disable, because the SCSI cable is already terminated at the end.

Refer to the information that come with the SCSI device for instructions about setting device jumpers or switches that control termination.

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