Destination Server Failover

Your replication plan may include replication to a server that is part of a highly-available group.

There are two common approaches to destination server failover:

1. Wide IP - AMPS replication works transparently with wide IP and many installations use wide IP for destination server failover. The advantage of this approach is that it requires no additional configuration in AMPS and redundant servers can be added or removed from the wide IP group without reconfiguring the instances that replicate to the group. A disadvantage to this approach is that failover can require several seconds and messages are not replicated during the time that it takes for failover to occur.

2. AMPS Failover - AMPS allows you to specify multiple downstream servers in the InetAddr element of a destination. In this case, AMPS treats the defined list of servers as a list of equivalent servers, listed in order of priority.

When multiple addresses are specified for a destination, each time AMPS needs to make a connection to a destination and there is no incoming connection from a server in that destination, AMPS starts at the beginning of the list and attempts to connect to each address in the list. If AMPS is unable to connect to any address in the list, AMPS waits for a timeout period, then begins again with the first server on the list. Each time AMPS reaches the end of the list without establishing a connection, AMPS increases the timeout period. If an incoming connection from one of the servers on the list exists, AMPS will use that connection for outgoing replication. If multiple incoming connections from servers in the list exist, AMPS will choose one of the incoming connections to use for outgoing traffic.

This capability allows you to easily set up replication to a highly-available group. If the server you are replicating to fails over, AMPS uses the prioritized list of servers to re-establish a connection.