AutoMate BPA Server 9 permits "Failover" capability in servers, systems or networks requiring continues accessibility and a high degree of reliability. Failover is the ability for an Agent to switch over automatically to a redundant or standby AutoMate BPA server component upon failure or abnormal termination of the previously active server component. Failover happens without human intervention. The second server will immediately take over the work of the first as soon as it detects a loss of communication.
AutoMate BPA Failover relies on the following conditions in order to work properly:
Two AutoMate BPA Execution Server components and at least one Agent.
A database back end is in use as the BPA datastore, and it is in a redundant, failover server itself so the data is always available.
Although not a requirement, it is recommended that BPA Development Tools, Agents and the external database resides on machines separate from the ones where the primary and secondary BPA Execution Server components are installed.
The Failover functionality is primarily Agent-based in that remote Agents are responsible for communicating with the Execution Server and are able to connect to a secondary or tertiary server if the primary server connection is lost. This is performed independent of the BPA Execution Server. Agents can be configured for up to three server host names (or IP addresses) to allow a hierarchal order of primary, secondary and tertiary servers. The different host names are stored in the registry under a single key value separated by semi-colons. The Agent will always attempt to connect to the primary host name first. If that is not available, the secondary, then tertiary server will be attempted. This process will cycle until the agent successfully connects to a server.
If the Agent connects to the primary server, and the connection to that server is lost, the Agent sets a timer for fifteen seconds and attempts to connect to the secondary and then tertiary servers as described above.
If the Agent connects to a secondary or tertiary server, a timer for thirty seconds is set. When the timer expires, a separate thread is started to test if the primary server is available. If it is, the connection is closed and the Agent reconnects to the primary server. If it is not, the Agent will stay connected to the secondary or tertiary server and perform connection to the primary server every 30 seconds until successful.
NOTE: Be aware, that careless Registry editing can make your system malfunction or even keep you from starting Windows. Proceed with caution.
On each machine where a BPA Agent is installed, create a backup of the registry.
After backing up the Registry go to the following Registry location:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Network Automation\BPA Agent 8\TaskService\Agent\Host
Right-click the Host string and select Modify.
Enter the primary, secondary and tertiary execution server names/IP addresses and their communication port. Each server name and port should be separated by a colon. Each server/port combination should be separated with a semi colon. For example, if specifying the server name (as opposed to the IP Address), enter the information in the following manner:
Exit the Registry for the current Agent machine and repeat the steps for all other Agent machines. The value data entered in the Host registry string must be identical on all Agent machines to ensure that Failover works properly.
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