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Document ID: GKEY-3H2GQZ |
PCServer704 - SCSI Drives
Applicable to: World-Wide
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-2 connector.
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Note | |
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Any information about SCSI drives also applies to other SCSI devices, such as scanners and printers. |
The SCSI CD-ROM drive that comes with the server connects to the 8-bit SCSI narrow connector on the upper SCSI backplane.
The disk-array models come with a RAID adapter, which provides two additional SCSI-2 connectors. The number of preinstalled SCSI hard disk drives might vary according to model. The disk-array models come with two integrated SCSI-2 controllers on the system board. Each SCSI-2 controller supports a SCSI-2 connector on the system board. The server comes with a 16-bit cable attached to each of the SCSI-2 connectors on the RAID controller; each cable connects to the 16-bit, wide connector on one of the SCSI backplanes. Also, disk-array models come with a 4-drop, SCSI narrow cable, which is already attached to the CD-ROM drive and the integrated SCSI-2 controller on the system board. This cable has three connectors available for attaching additional devices.
SCSI IDs
Each SCSI device that is connected to the integrated SCSI-2 controllers needs a unique identification (ID) so that the controllers can identify the devices and ensure that different devices do not attempt to transfer data at the same time. To set IDs for SCSI devices, refer to the instructions that come with those devices.
The SCSI ID for the preinstalled CD-ROM drive is set to 5. The SCSI ID for the backplane is set to 6. The SCSI ID for the SCSI-2 controller is set to 7. The server automatically sets SCSI IDs for hot-swap drives, according to the jumper settings on the SCSI-2 backplanes. If you need to set SCSI IDs for SCSI devices, refer to the instructions that come with these devices.
The server uses the SCSI IDs to send status information to the indicator lights above each hot-swap bay.
Jumpers on each backplane control the SCSI IDs for the bays. To resolve any SCSI ID conflict that might occur, you can change the default ID addresses of the drives by changing the jumper settings on the SCSI backplane. Each SCSI ID must be unique for each drive that you connect to a given backplane.
Each of the two SCSI backplanes in the server supports six of the hot-swap bays. The top six hot-swap drives connect to the upper backplane. The lower six drives connect to the lower backplane. In each set of two rows, the drives are numbered 1 to 6.
Table 2 shows the SCSI IDs that you can use for hot-swap drives.
Table 2. SCSI IDs for Hot-Swap Drives
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J3 |
J4 |
HD1 |
HD2 |
HD3 |
HD4 |
HD5 |
HD6 |
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1-2 |
1-2 |
0 |
1 |
10 |
3 |
4 |
13 |
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1-2i |
2-3i |
0 |
1 |
2 |
3 |
4 |
5 |
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2-3 |
2-3 |
8 |
9 |
2 |
11 |
12 |
5 |
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2-3ii |
1-2ii |
8 |
9 |
10 |
11 |
12 |
13 |
The processing sequence for SCSI devices is set through the SCSISelect Utility program (refer to the Server SCSI Software User's Guide for more information). The sequence proceeds from the lowest SCSI ID to the highest (0 to 6, then 8 to 15).
Termination (Internal SCSI Devices)
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.
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Note | |
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All of the preinstalled hot-swap drives in the server have automatic termination. |
If you attach internal SCSI devices to one of the SCSI-2 internal connectors in a non-disk-array model, you must terminate the last internal device on the bus (cable) and disable the termination on the other devices connected to the internal SCSI controller. The SCSI-2 controller is already terminated.
Refer to the instructions that came with the SCSI device for more information about termination. Refer to the User's Reference for additional information about the server's SCSI subsystem.
SCSI Drive Status Indicator Descriptions (LEDs)
You can locate a faulty hot-swap hard disk drive by checking the status indicators above each of the 12 drive bays. Refer to the following table.
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SCSI drive |
SCSI drive Green LED |
SCSI drive Amber LED |
Description and required action (if necessary) |
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On |
Off |
Off |
The drive is present with power. |
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On |
Blinking |
Off |
The drive is present with power, and is being accessed. |
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Off |
Off |
On |
You might need to replace the drive. A steady SCSI drive faulty indicator means that the drive has a problem. The drive has no power. |
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On |
Off |
Slow |
Do not replace the drive. A slowly blinking SCSI drive faulty indicator means that the drive has just been replaced and is in recovery mode (that is, the disk array is being rebuilt). The drive has power. |
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Off |
Off |
Off |
There is no drive installed in the bay. If a drive is installed but the LEDs are off, check the cable connections to the backplane. |
Termination (Internal SCSI Devices)
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.
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Note | |
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All of the preinstalled hot-swap drives in your server have automatic termination. |
If you attach internal SCSI devices to one of the SCSI-2 internal connectors in a non-disk-array model, you must terminate the last internal device on the bus (cable) and disable the termination on the other devices connected to the internal SCSI controller. The SCSI-2 controller is already terminated.
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- A 16-bit cable connects the backplane to the SCSI-2 controller. |
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Search Keywords |
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Hint Category |
Configuration, Hard Drives, Hardware Maintenance Information, SCSI | |
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Date Created |
13-05-97 | |
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Last Updated |
25-01-99 | |
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Revision Date |
24-01-2000 | |
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Brand |
IBM PC Server | |
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Product Family |
PC Server 704 | |
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Machine Type |
8650 | |
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Model |
Various | |
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TypeModel |
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Retain Tip (if applicable) |
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Reverse Doclinks |