Dell PowerVault 770N (Deskside NAS Appliance) - Manual (Page 21)

Split-Bus Module
Your system supports three SCSI bus modes controlled by the split-bus module:
Joined-bus mode
Split-bus mode
Cluster mode
These modes are controlled by the position of the bus configuration switch when the system is turned on.
Figure 2-4 illustrates the switch position for each mode.
Figure 2-4. Bus Configuration Switch Modes