HA-JDBC: High-Availability JDBC

Overview

HA-JDBC is a JDBC proxy that provides light-weight, transparent, fault tolerant clustering capability to any underlying JDBC driver.

Supports any database accessible via JDBC.
High fault tolerance - a database cluster can lose a node without failing/corrupting any transactions.
Live activation/deactivation allows for maintenance/upgrading of a database node without loss of service.
Improves performance of concurrent read-access by distributing load across individual nodes.
Works with Java 1.6 and 1.7 and fully supports JDBC 4.1.
Pluggable strategies for synchronizing a failed database node.
Exposes JMX management interface to allow administration of databases and clusters.
Ability to add/subtract database nodes to/from a cluster at runtime.
Can be configured to auto-activate failed database nodes during scheduled off-peak times.
Open source (LGPL).

Not overly fond of HA-JDBC? Check out these alternative projects:

pgpool-II: Replication middleware for PostgreSQL
Tungsten Replicator: A high performance data replication engine for MySQL
MySQL Cluster: Fault tolerant database architecture using NDB storage engine
H2 Clustering: A simple clustering/high-availability mechanism for H2