SCSI ID selector switch usage - Servers

Resolving The Problem

Source

RETAIN tip: H1964

Symptom

When a half-high (HH) LTO2 (Options 25R0005 and 39M5658) tape drive is installed into either the 4559 or 8765 tape enclosure and a SCSI ID connector on the tape enclosure is connected to HH LTO2, the SCSI ID bits are inverted left to right as shown below so that the controller sees a different SCSI ID than the SCSI ID Selector Switch is set for:

SCSI ID Sel SW	SCSI ID reported to controller
0 (0000)	0 (0000)
1 (0001)	8 (1000)
2 (0010)	4 (0100)
3 (0011)	12 (1100)
13 (1101)	11 (1011)
14 (1110)	7 (0111)
15 (1111)	15 (1111)

Affected configurations

This tip is not hardware specific.

The system is configured with one or more of the following IBM Options:

This tip is not software specific.

Solution

Contact the IBM Support Center or your service provider and order replacement part number 43W8472 SCSI ID Selector Adapter.

This is a bit adapter cable that connects inside the tape enclosure between the SCSI ID Selector Switch cable and the SCSI ID pin block on the tape backup unit.

Note: For the Support Center in the United States, contact 1-800-IBM-SERV (1-800-426-7378). The IBM Directory of Worldwide Contacts is available at the following URL:

http://www.ibm.com/planetwide/

The 43W8472 SCSI ID Selector Adapter consists of a male and female 8-pin connector block wired together using three black, a yellow, green, orange, and purple wires.

Line up the corresponding wires on the SCSI ID Selector Switch cable with the 43W8472 SCSI ID Selector Adapter wires. Pin 0 is identified by a small white dot on both ends of the new cable.

Tape backup unit SCSI ID bit pins are illustrated on each tape drive manufactured. Line up SCSI ID Pin 0 of the tape backup unit with the white dot on the 43W8472 SCSI ID Selector Adapter connector.

Workaround

Do not use the SCSI ID selector switch on the tape enclosure.

Do not attach the SCSI ID Selector switch cable to the tape backup device. Instead, affix the jumpers that came in the tape backup device kit to the tape backup unit's SCSI ID pin block to set the SCSI ID's. Instructions are found in the User's Guide.

Additional information

Users reported that the actual SCSI ID of IBM HH LTO2 (Options 25R0005 and 39M5658) is different than the SCSI ID on 4559-1UX and 8765-1UX. The reason is that the SCSI ID bit assignment of the jumper on the HH LTO2 is different than other tape drives.

This does not occur when the user utilizes the jumper pins for setting the SCSI ID. However, if an HH LTO2 is installed into tape enclosure and SCSI ID connector on the tape enclosure is connected to HH LTO2, all reported SCSI ID bits are inverted from left to right.

Connector SCSI ID	Actual SCSI ID
0 (0000)	0 (0000)
1 (0001)	8 (1000)
2 (0010)	4 (0100)
3 (0011)	12 (1100)
13 (1101)	11 (1011)
14 (1110)	7 (0111)
15 (1111)	15 (1111)

Inserting the connector upside-down does not resolve the issue.