High Availability Features

Remote Node Access

The Remote Node access feature provided by the ACC Mux Subsystem provides the ability to access remote ACC Mux ports in the same manner as local Mux ports are accessed.

This feature is only available to application programs that use the ZCOM programmatic interface. It requires that the local and remote systems be connected via at least one LAN. The znode daemon must be running on the local node and any remote nodes that will be accessed. Note that it is not required that the local system have an ACC Mux card installed in order to use this feature.

Refer to the ACC Utilities Reference Guide for more information on the znode daemon, and related configuration information. If the ACC Protocol for Application Developers product is installed, refer to the ACC Programmer's Reference Guide for information on using the ZCOM programmatic interface to make requests to remote nodes.

Daemon Monitoring and Recovery

The ACC Mux Subsystem and related product options provide a number of daemons that provide critical functionality. The zmasterd program is provided to automate the starting of the daemons, and to coordinate the shutting down of the daemons. It also restarts daemons that terminate unexpectedly.

Refer to the ACC Utilities Reference Guide for more information on the zmasterd feature.

Dual Interface Configuration

The Dual Interface options for ACC Mux cards provide the ability to connect two Mux cards to the network in a high-availability configuration. Such connections should be used to give one Mux card access (but ONLY one), while the other remains in a hot-standby mode. In the case that the “live” Mux card fails, the other card can be activated with little or no interruption of service. It is possible to allow one 8-channel system access to some of the Mux ports on the panel, and the second system access to the remaining ports.

This feature requires that initially the standby card configures the port for “loopback”, while the “live” card configures the port for “RS-232”, “RS-449”, etc. It also may require the use of the watch daemon.

Refer to Chapter 4 “Dual Interface Configurations” for more information on using the Dual Interface configurations.

Refer to the ACC Utilities Reference Guide for more information on the watch daemon, and related configuration information.