Setting SCSI IDs and Termination - PC Server 320

Resolving The Problem

The PC Server 320 comes with one of two possible configurations; disk-array and non-disk-array models.

Setting SCSI IDs in non-disk-array configurations

If you install additional SCSI devices in a non-disk-array model, you must set a unique identification (ID) for each SCSI device that you connect to the SCSI-2 Fast/Wide PCI-Bus adapter, so that the SCSI-2 adapter can identify the devices and ensure that different devices do not attempt to transfer data at the same time.

For non-disk-array models, Fast/Wide (16-bit) devices support SCSI IDs 0 to 15; narrow (8-bit) devices support SCSI IDs 0 to 7.

Startup Drive

The drive from which you will start the non-disk-array server (also known as the boot or startup drive) should have a SCSI ID of 6. Therefore, if the server was not supplied with a preinstalled hard disk drive and you install hard disk drives, set the SCSI ID of the first drive (the boot drive) to 6. Refer to the instructions supplied with the SCSI devices for information about setting a SCSI ID.

If the BIOS is version M54PE_08 or earlier and you have two PCI SCSI adapters installed in the PCI slots, the system will start from the hard disk drive attached to the SCSI adapter with the least amount of Read-only memory (ROM) and the lowest ROM address space. (In the case of equal ROM size, the system scans from slot 1 to 3 and assigns slot 1 as the lowest ROM address.) Therefore, in order for the system to load the operating system correctly, connect the startup drive to the SCSI adapter with the lowest ROM address space. If the version of BIOS is later than M54PE_08, and you have two PCI SCSI adapters installed in the PCI slots, the system will start from the hard disk drive attached to the SCSI adapter in descending order from slot 3 to slot 1.

Setting SCSI IDs in disk-array configurations (Or non-disk-array models with the hot-swap bay option installed)

The SCSI IDs in disk-array models with the SCSI-2 Fast/Wide PCI-Bus Adapter are hard-coded in the backplane of the hot-swap bay and preset for the CD-ROM drive. Do not attempt to change the SCSI IDs for internal SCSI devices on disk-array models.

For disk-array models, the external channel connector supports SCSI IDs 0 to 7; the internal channel connector (only one of the two internal channel connectors can be used at one time) also supports SCSI IDs 0 to 7. Devices attached to the external connector and internal connector are accessed independently. A SCSI ID of 0 assigned to an internal device and a SCSI ID of 0 assigned to an external device does not create a conflict.

Startup Drive

If the disk-array model was supplied with a preinstalled hard disk drive in bay 1, this drive is the startup drive, and it already has a SCSI ID of 0.

The SCSI-2 adapter in the server has two internal connectors and one external connector:

• On non-disk-array models: the SCSI-2 adapter has one internal connector for an 8-bit cable, and one internal connector for a 16-bit cable. Non-disk-array models that are supplied with a preinstalled wide hard disk drive use a 16-bit internal connector. Non-disk-array models that are not supplied with a preinstalled hard disk drive or supplied with a narrow hard disk drive use an 8-bit internal connector.
• On the disk-array models: the SCSI-2 adapter has two internal connectors for 16-bit cables. To keep the external channel available for use on the preinstalled RAID adapter, use Channel 2 for connecting internal SCSI devices.

NOTE: You can use only one of the two internal SCSI connectors on the SCSI-2 adapter if you connect both internal and external devices.

On all models, the external connector is for 16-bit cable.

The SCSI-2 Fast/Wide PCI Adapter supports a total of seven 8-bit or fifteen 16-bit SCSI devices. The SCSI-2 Fast/Wide PCI-Bus Adapter supports a total of fourteen 16-bit SCSI devices.

Termination (Internal and External SCSI Devices)

The requirements for terminating SCSI devices on non-disk-array models are:

The devices at both ends of the SCSI bus must be terminated. If you attach SCSI devices (internal or external), you must terminate the last device in the chain. You must remove the termination from the other devices within the chain. If you attach external devices to a non-disk-array model with internal devices attached, you must also change the termination setting of the SCSI-2 adapter from the default in the SCSISelect utility program.

If you attach internal SCSI devices to only one of the SCSI-2 adapter internal connectors, you must terminate the last internal device on the bus (cable) and disable the termination on the other devices connected to the internal SCSI connector. The SCSI-2 adapter is already terminated.

If you attach internal SCSI devices to both of the SCSI-2 adapter internal connectors, you must terminate the last internal device on each internal cable and disable the termination on the other devices connected to the internal SCSI connectors. You must also change the termination setting of the SCSI-2 adapter from the default in the SCSISelect utility program.

The requirements for terminating SCSI devices on disk-array models are:
Termination on disk-array models is automatically set.

In non-disk-array models that are not supplied with a hard disk drive:
The CD-ROM drive is terminated.
A narrow (8-bit) cable is provided in these models.

If you install 8-bit drives above the CD-ROM drive in bays 5-9, remove the termination from those drives. If you install a drive in bay 1, you must terminate that drive and remove the termination from the CD-ROM drive.

If you install a 16-bit device, you must purchase a 16-bit cable and a 16-bit to 8-bit SCSI Internal Converter to connect the CD-ROM drive to the 16-bit cable.

Refer to the instructions supplied with the SCSI device for more information about termination.