Configuring the server group signaling option
When object definition changes are made on the administrative server in a server group, other members of the group can be notified either by a database posting or by a signal:
By default, handles these changes
Reduces server activity when object definition changes are communicated between servers and reduces the number of cache reloads when a series of changes is made. A delay occurs before other members of the server group pick up the changes.
Server definition changes – such as changes to forms, active links, filters, and escalations – and user group changes.
Other servers are notified of changes immediately. No delay occurs in resynchronization or updating definitions.
All other changes, such as Alert registration and DSO activity.
You can configure the server to use signaling for all changes, including server object changes. See Configuring the server group signaling option.
Server group signaling introduction
Servers in a server group use the arsignald daemon to notify other members of the group about signaled changes. This daemon (arsignald.exe on Windows and arsignald on UNIX) is a persistent process started by the AR System server at server start up. It maintains a pipe to the associated AR System server and handles all signals to the other members of the server group. Therefore, signaling between members of a server group requires only one additional server process per server.
In previous releases, server group signaling was performed by the arsignal program, which caused a separate process to be spawned and then closed down for every change. This could significantly impact resources on the host computer. The arsignal program is still available for use by AR System workflow, but is no longer used for server group signaling.
Using signals for all changes in server groups
The Server-Group-Signal-Option server configuration file option tells the server whether to use arsignald for all signals instead of using a combination of signaling and database posting. If this option is set to true (T), all server object changes are communicated by arsignald. Use this option to avoid any delay in communicating server object changes to other servers in the server group.
To use signals for all changes in server groups, add the following line to the ar.conf (ar.cfg) file of each server in the server group:
If this option is set to false (F) or is not included, server group signals are accomplished by the default method described in this section.
See also Server-Group-Signal-Option.
Form, workflow, and escalation time changes can significantly increase the workload on a production server. In a server group environment, that effect is magnified when other servers are notified of the changes and they recache definitions from the database. Consider this when planning changes of this type.
Disabling automatic signaling in server groups
Signals triggered by certain object definition changes on the administrative server can cause recaches on target servers that significantly increase memory use temporarily. This increase can adversely affect the response time of the target servers. To change object definitions on the administrative server without impairing the performance of target servers, you can disable automatic signaling from arsignald and the database for changes to the following data:
- Archive definitions
- Escalation scheduling
- Form definitions
- Group information from the database
- Workflow definitions
Signals triggered by changes to user, licensing, and computed group information are not disabled.
Later, when memory use is low, you can manually send the signals to the target servers by using the arsignal program.
To disable automatic signaling for the specified changes, add the following line to the ar.conf (ar.cfg) file of each server in the server group:
If this option is set to false (F) or is not included (the default), automatic signaling remains in effect for all object definition changes.
See also Disable-ARSignals.