Application Failover in DataDirect ODBC Drivers

DataDirect Failover

Failover Alternatives

Ensures application reliability and data integrity
DataDirect’s high-quality approach guarantees data consistency and validity by ensuring that the alternate server is an exact mirror of the primary server with respect to transaction state. If for some reason the states don’t match, the driver will detect this and allow the application to take the appropriate action.

Reliability issues have been detected in various failover solutions because they lack the level of quality and functionality needed to detect changes in data state.

Completely manages failover
With DataDirect, application failover is managed completely by the driver without additional coding or server dependencies:

• Manages the re-connection to an alternate server list (which may include multiple reconnect attempts)
• Checks that the state of the data in the alternate server is consistent with the application
• Re-prepares the Select statement, re-executes the Select statement, and re-positions the cursor to the request that was being processed

Relies on additional coding and expensive server configurations such as Oracle Real Application Clusters (RAC), Microsoft Cluster Server (MSCS), and DB2 High Availability Disaster Recovery (HADR).

Provides a consistent, standards-based approach
DataDirect’s failover implementation provides consistency regardless of database or operating environment to help reduce application development costs.

In addition, DataDirect simplifies and standardizes the return code values, which greatly reduces the application code necessary to implement failover, and makes it easy to provide failover in heterogeneous database environments.

Proprietary approach must be implemented for each database supported. This limits future database flexibility and includes database-specific error messages that require database-specific application code.

Gives you flexibility
DataDirect Application Failover is completely configurable and provides multiple failover options. You configure the list of alternate servers, number of re-try attempts and the associated wait period, and the failover options, including:

• Connection Failover - Ensures that new connections can be established, even if the primary server is not available.
• Extended Connection Failover - Supports new connections as well as lost connections by connecting to an alternate server while also restoring the state of a lost connection.
• Select Failover - Fails over to an alternate server while preserving the state of the connection, along with the work being performed by the Select statement. This includes re-positioning the cursor to the next row in a row that was returned by a select statement.

Various approaches may be hardware or software based, may vary in scope (project or enterprise), and may vary vastly in cost and complexity.

Reduces application development costs
Because the DataDirect driver manages failover, you won’t have to implement time-consuming proprietary code in the application or costly server configurations provided by the database vendors.

Relies on expensive server configurations and database-specific application code, which results in higher cost of development.

In addition, failover support is only provided in drivers that are based on database client libraries, resulting in inferior performance and increased deployment and maintenance costs.

Offers Client Load Balancing
Works with failover to help distribute new connections so that no one server is overwhelmed with connection requests.

Competitive drivers don’t provide client load balancing.