Connect Powervault 220s to a server

Cabling Your System for Joined-Bus, Split-Bus, or Cluster Mode

How you cable your storage system to your host system(s) depends on the bus configuration you choose: joined-bus, split-bus, or cluster.

  • A joined-bus configuration is one in which two SCSI buses are joined to form one contiguous bus.
  • A split-bus configuration enables you to connect your storage system to either one server with a multichannel RAID controller, or to two servers. However, if one server fails, information controlled by that server is inaccessible.
  • A cluster configuration offers multiple paths to the system, which provides high data availability.

Joined-Bus Configuration


Split-Bus Configuration (One Server)

Cluster Configuration or Split-Bus Configuration (Two Servers)

SCSI ID Assignments

Configuration Cables
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Joined-bus 1                 H S            
Split-bus—primary EMM 1                 H S            
Split-bus—secondary EMM 1                 H S            
Cluster 2 S               H H            
NOTE: The unshaded SCSI IDs are available for hard-drive use as indicated for each configuration. The reserved SCSI IDs are used as follows:
H = used by the host system initiator.
S = used by the storage system SES.

SCSI ID Numbers and Associated Hard Drives 


Split-Bus Module Modes

Mode LED Icon Position of Bus Configuration Switch Function
Joined-bus mode  


Top LVD termination on the split-bus module is disabled, electrically joining the two SCSI buses to form one contiguous bus. In this mode, neither the split-bus nor the cluster LED indicators on the front of the system are illuminated.
Split-bus mode  


Center LVD termination on the split-bus module is enabled and the two buses are electrically isolated, resulting in two seven-drive SCSI buses. The split-bus LED indicator on the front of the system is illuminated while the system is in split-bus mode.
Cluster mode  


Bottom LVD termination is disabled and the buses are electrically joined. The cluster LED on the front of the system is illuminated while the system is in cluster mode.
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