MySQL is continuing to push into the business market with the release of a clustered version of its hugely popular open-source database.

Available today in a preview version, MySQL Cluster will have a proper release toward the end of the year. In the meantime, the company claims that it will combine the MySQL database with a clustering architecture for 99.999 percent availability for mission-critical apps.

"The increasing volume of critical data, transactions and users in today’s 'always on' Internet and networked environments has made high availability a necessity for companies,” said CEO Marten Mickos. "MySQL Cluster has the availability, scalability and throughput for the most demanding applications, and its affordability makes clustering an option for any organization. This product demonstrates our commitment to make superior database management available and affordable to all."

The database features a distributed in-memory clustering architecture, with response times of five to ten milliseconds and a throughput of 100,000 replicated transactions per second on a four-node cluster with two CPUs per node.

"For the application developer, failover is automatic," said Zack Urlocker, MySQL vice president of marketing. "They don’t have to worry about underlying failure detection algorithms or how the database is distributed across multiple nodes,” .

Data can be distributed over a group of interconnected databases on multiple servers or nodes. Companies have been testing the database in a 48-node configuration, according to MySQL. The goal is to make clustering mainstream, the company said.

MySQL is offering MySQL Cluster under its "dual license" business model, in which it is provided at no cost under the free software/open source GNU General Public License for open source projects and under a commercial license for software vendors and commercial customers. The commercial license will be priced at less than $5,000 per processor, MySQL said. Under the GPL license, users must publish source code for their applications.

The product runs on Linux, Windows, Solaris, and OS X. Hardware platforms covered include 32- and 64-bit Intel systems, PowerPC, and Sparc.