Compaq AA-RHGWC-TE manual Connecting the TL894 Tape Library to the Shared Scsi Bus

installing an HD68 SCSI bus terminator on the SCSI bus port connector on the cabinet exterior.

This is not wrong, but by reconfiguring in this manner, the length of the SCSI bus is increased by 1.5 meters, and may cause problems if SCSI bus length is of concern.

In a future revision of the previously mentioned guide, the bus configuration figures will be modified to show all SCSI buses terminated at the tape drives.

8.9.4 Connecting the TL894 Tape Library to the Shared SCSI Bus

The TL894 tape libraries have up to 3 meters of internal SCSI cabling per SCSI bus. Because of the internal SCSI cable lengths, it is not possible to use a trilink connector or Y cable to terminate the SCSI bus external to the library as is done with other devices on the shared SCSI bus. Each SCSI bus must be terminated internal to the tape library, at the tape drive itself with the installed SCSI terminators. Therefore, TruCluster Server clusters using the TL894 tape library must ensure that the tape library is on the end of the shared SCSI bus.

In a TruCluster Server cluster with a TL894 tape library, the member systems and StorageWorks enclosures or RAID subsystems may be isolated from the shared SCSI bus because they use trilink connectors or Y cables. However, the ASE must be shut down to remove a tape loader from the shared bus.

Figure 8–13 shows a sample TruCluster Server cluster using a TL894 tape library. In the sample configuration, the tape library has been connected in the two-bus mode by jumpering tape drive 0 to tape drive 1 and tape drive 2 to tape drive 3 (see Section 8.9.3 and Figure 8–12). The two SCSI buses are left at the default SCSI IDs and terminated at drives 1 and 3 with the installed terminators (part number 0415619).

To add a TL894 to a shared SCSI bus, select the member system or storage device that will be the next to last device on the shared SCSI bus. Connect a BN21K or BN21L cable between the Y cable on that device to the appropriate tape library port.

Configuring a Shared SCSI Bus for Tape Drive Use 8–41