The following software products are required on both the primary and secondary OpenTP1 systems (TP1/Server Base) when using the System Switchover facility:

• HAmonitor, TP1/High Availability
  These are required whenever the System Switchover facility is used.
  
• TP1/NET/High Availability
  This is required for using the System Switchover facility and the message control facilities (TP1/Message Control and TP1/NET/Library).
  

The following hardware is used in common by the primary and secondary systems:

• Shared disk device
  Shared disk device
  
• LAN
  Used for the name service of OpenTP1. The LAN is used for OpenTP1 communication. An additional LAN (called a maintenance LAN) is necessary for maintaining multiple systems. The maintenance LAN is not used for OpenTP1 communication; it is mainly used for remote access to the standby system.
  
• Monitoring path
  An interface for communicating the status of each system. The monitoring path is used by HAmonitor. The monitoring path can be either the monitoring link or the monitoring LAN.
  

The figure below shows the configuration when using the System Switchover facility. For the primary and secondary systems to monitor each other, hardware and software additional to that shown in the figure are required. For details about the required resources, see the relevant HAmonitor manuals.

Figure 6-2 Configuration when using the System Switchover facility