Compaq AA-RHGWC-TE - Manual (Page 255)

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