Assumes the user is running SQL server already for database backend.
On existing (or primary) Central, edit the preferences file, adding
where <somename> is some unique name across the Centrals in the high availability cluster, e.g. simply "1" or "central1"
The Automatic Update feature cannot be used when the Central service is in High Availability setup
The procedure for updating the Central servers in High Availability is as follows:
Now, both servers should be upgraded and again in High Availability mode.
By default the Central instances update the heartbeat timestamp in the database every 10 seconds.
The local time of the cluster member machines are used to update the heartbeat timestamp in the database. It's crucial that the cluster member machines have a synchronized time.
This can be tweaked in the preferences.cfg of the M&M Centrals (min 5 sec max 15 sec).
The preferences XML tag is e.g. for the default 10 sec:
<HeartbeatInterval value=“10” />
When a M&M Central stops to write the heartbeat timestamp to the DB the “HeartbeatMaxAllowedDowntime" is used to determine if a failover to the next valid Central in the list will be done.
Valid means in this case that the Central is a cluster member and writing its heartbeat timestamp to the DB.
The default max downtime is 30 seconds, i.e. when the
current time UTC - heartbeat timestamp UTC > HeartbeatMaxAllowedDowntime(default 30 sec), then an automatic failover will be triggered.
The default max downtime can be overwritten in the preferences.cfg of the Central instances:
<HeartbeatMaxAllowedDowntime value=“30” />
Values between 20 and 120 seconds are allowed.