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Installation & Configuration
Connecting SCSI Cables and Terminators
20
Installation
Table 2. SCSI Bus Requirements
Interface
Type
1
SCSI Cabling
Total Length
2
Number
of Devices
3
SCSI
Terminator
4
SE 6 m HBA + 7 SE (Active)
DF 25 m HBA + 15 DF (Passive)
Notes:
1. SE = single-ended narrow; DF = fast/wide differential.
2. The total length of SCSI cabling is equal to the equivalent internal cable length (0.9 meter per
internal bus, or 1.0 meter per storage system) plus the external cable length. To connect internal
buses A and B, a bus interconnect cable is required.
3. Depending on the type of interface used, you may not be able to fully load the storage system with 1-
inch storage modules. For example, on a single-ended bus, you must leave one slot empty, since only
seven devices are supported in addition to the HBA. If two storage systems are connected on a
differential bus, eight slots can be filled in the first storage system and seven more slots can be filled
in the second storage system.
4. Each end of the SCSI bus must be terminated. The HBA card is one end of the bus. It includes its own
termination and also provides termination power. The other end of the bus is one of the SCSI
connectors on the rear panel of the storage system. Depending on the configuration, a 68-pin high
density SCSI terminator must be connected to one or both of these connectors. Refer to your host
system documentation for exact terminator specifications.
Connect SCSI cables (see Figure 13 through Figure 15) and SCSI terminators (see Figure 16) to the
storage system in one of the following configurations:
• Single Bus: Bus B is connected to one host bus adapter (HBA), bus B and bus A are interconnected,
and bus A is terminated with a SCSI terminator (see Figure 13). Two storage systems can be
connected together on a common SCSI bus (see Figure 14).
• Split Bus: Bus A and bus B are connected to two separate HBAs, each terminated with a SCSI
terminator (see Figure 15). Both buses can have the same SCSI interface or can have different SCSI
interfaces.