Open SCSI Integrator's Manual for NonStop S-Series Servers

Integrating Hardware
Open SCSI Integrator’s Manual for NonStop Servers—422988-002
3-5
SCSI Configurations on the 6760 ServerNet/DA
SCSI Configurations on the 6760 ServerNet/DA
The 6760 ServerNet/DA differs from the PMF CRU and the IOMF CRU in the
following ways:
•
The terminators on its SCSI ports are built into the SCSI SAC.
•
Each port connects to a separate SCSI SAC.
•
Terminators are built into its SCSI SACs, so the 6760 ServerNet/DA does not need a
passthrough terminator.
•
A pair of 6760 ServerNet/DAs can support both single-path configurations and dual-
path configurations simultaneously.
Figure 3-4
shows an example of both a single-path SCSI bus configuration and a dual-
path SCSI bus configuration on the same pair of adapters.
Single-Path Configuration
The single-path configuration shows an external terminator installed on the last device
in the chain.
Dual-Path Configuration
The dual-path configuration shows that each device is connected to the SCSI bus
through two different SACs. Termination is provided at each end of the SCSI bus by the
terminators built into the 6760 ServerNet/DA SCSI SAC.
Because the 6760 Servernet/DA accesses only one ServerNet fabric, a dual-path
configuration is more fault-tolerant if it includes:
•
one 6760 ServerNet/DA adapter connected to the X fabric (that is, installed in slot
51 or 53)
•
one 6760 ServerNet/DA adapter connected to the Y fabric (that is, installed in slot
52 or 54)
In a dual-path configuration, ensure that you do not connect a device to two SCSI SACs
that have the same SCSI ID. For information about SCSI IDs, refer to Assigning SCSI
ID Numbers on page 3-7.