You can use nonstop processes (NWP) to increase your system reliability. A specific license is required for this purpose. In nonstop operation, only the work processes (WPs) of one computer are active. The processes of a different computer (nonstop processes) are available upon request. If the primary computer that includes the active WPs fails, the nonstop processes take over their role. As opposed to a usual situation of parallel operation, the system configuration NonStop Server does not use the WPs of all computers. The WPs of any computer are always in the mode "hot standby."
You can get more information about the server processes that you are using in the Processes & Usage page of the Administation perspective. Type "N" processes are nonstop processes, see also The Processes List
The following example intends to explain how a NonStop Server works:
Let's assume that the server processes of an AE system are located on two computers. A WP of computer A connects first and obtains the status of a primary work process (PWP). All other server processes of computer A are set active. All WPs of computer B automatically become nonstop processes. If computer A goes offline, the nonstop processes become active WPs, and one of them obtains the status of a PWP.
Notes:
- Server processes change to NonStop Server mode if you have the relevant licenses. No specifications are required to install and configure the Automation Engine.
- The starting order of the server processes is decisive for the classification of server processes. The server processes of the computer whose WP starts first are set active. The other computer, including its server processes, becomes the NonStop Server.
- Only WPs can become nonstop processes. CPs are always active. At least one CP should be available on the computer with the nonstop processes in order to ensure that the nonstop processes can proceed.
- The NonStop Server takes over processing if it does not receive any message from the PWP for a specified period of time. You can define this time span in the Automation Engine's INI file by using the parameter alivetimeout= ( [TCP/IP] section). Automic strongly recommends changing the default value only if necessary.
Script
You can find out the type of a server process by using he script element GET_UC_SETTING. Return code "N" is supplied if the server process is a nonstop process.
See also: