Calculating HealthChecker Maximum
The following formula can help you compute the maximum time in milliseconds it will take HealthChecker to discover failed or disconnected remote nodes:
Max Time = (ping.idletime) + socketConnectCount * [(ping.interval * ping.probes)
+ (socketConnectTimeout * ping.interval)]
Note the following about the formula:
The response time to a socket-connection attempt is less than or equal to
(socketConnectTimeout * ping.interval). For calculating the worst-case scenario (absolute maximum time), the equality is used. In most real-world situations the socket-connect response time is likely to be close to 0 and the formula can be simplified to the following:
Max Time = (ping.idletime) + [socketConnectCount * (ping.interval *
ping.probes) + ping.interval]
ping.idletime, the trigger for the full HealthChecker process, is counted once since it is in effect only once each time the process is triggered.
socketConnectCount is a multiplier that is in incremented as long as a positive response is received for each socket connection attempt.
The formula yields an ideal value, since slight variations in actual times can occur.
To prevent clients from disconnecting too quickly in a situation where an active server is temporarily disconnected from both the backup server and those clients, ensure that the Max Time for L1->L2 is approximately 8-12 seconds longer than for L2->L2. If the values are too close together, then in certain situations the active server may kill the backup and refuse to allow clients to reconnect.