HA synchronization
The master node pushes most of its configuration to the other member nodes. This is known as synchronization. Synchronization occurs immediately when an appliance joins the cluster, and thereafter every 30 seconds. Synchronization includes:
• Core CLI-style configuration file (fadc_system.conf)
• X.509 certificates, certificate signing request files (CSR), and private keys
• Layer 4 connection state and Layer 7 persistence
For most settings, you configure only the primary node, and its settings are pushed to other members. You might log into the system for the other member in the following situations:
• To configure settings that are not synchronized
• To view log messages recorded about the member node itself on its own hard disk
• To view traffic reports for traffic processed by the member node
Table 83 summarizes the configuration settings that are not synchronized. All other configuration settings are synchronized.
Table 83: HA settings that are not synchronized
Setting | Explanation |
Hostname | The hostnames for member nodes are unique. |
Management interfaces | The management network interface IP addresses for cluster nodes are unique. |
SNMP system information | Each member node has its own SNMP system information. |
HA settings | Most the HA configuration is not synchronized in order for the nodes to be identified uniquely. |
Error Page | You can upload a file that contains a custom error page and add it to the configuration of a virtual server that load balances by application layer. The file you upload is not synchronized. |
In addition to the HA configuration, some data is also not synchronized:
• Log messages—These describe events that happened on that specific appliance. After a failover, you might notice that there is a gap in the original active appliance’s log files that corresponds to the period of its down time. Log messages created during the time when the standby was acting as the active appliance (if you have configured local log storage) are stored there, on the original standby appliance.
• Generated reports—Like the log messages that they are based upon, reports also describe events that happened on that specific appliance. As such, report settings are synchronized, but report output is not.