Connection failover allows an application to connect to an alternate, or backup, database server if the primary database server is unavailable, for example, because of a hardware failure or traffic overload. Connection failover ensures that the data on which your critical ADO applications depend is always available.
To configure connection failover, you must specify a list of alternate database servers that are tried at connection time if the primary OpenAccess SDK Server is not accepting connections. To do this, specify the Alternate Servers connection option on the Options tab of the Setup dialog box or in the connection string. (See Configuring ADO Client Data Sources for details.) Connection attempts continue until a connection is successfully established or until all the database servers in the list have been tried once (the default).
Important: If you specify an LDAP server and also enable connection failover, the alternate servers must be LDAP servers. The data provider will access the servers using the LDAP protocol.
Optionally, you can specify the following additional connection failover features:
The number of times the ADO Client attempts to connect to the primary and alternate OpenAccess SDK Servers after the initial unsuccessful connection attempt. By default, the ADO data provider does not retry. See Using Connection Retry for more information.
The wait interval, in seconds, between attempts to connect to the primary and alternate database servers. The default interval is 3 seconds. See Using Connection Retry for more information.
Whether the ADO Client will use client load balancing in its attempts to connect to primary and alternate OpenAccess SDK Servers. If load balancing is enabled, the ADO Client uses a random pattern instead of a sequential pattern in its attempts to connect. The default value is not to use load balancing. See Using Client Load Balancing for more information.
The number of times the ADO Client attempts to connect to the primary and alternate OpenAccess SDK Servers after the initial unsuccessful connection attempt. By default, the ADO data provider does not retry. See Using Connection Retry for more information.