Clustra Offers Five-Nines Reliability

In today's online world, customer loyalty is hard to find. In this climate, five minutes of downtime could mean the loss of a customer forever. Clustra Systems Inc. believes it has an answer to that problem: a database solution that averages only two minutes of downtime per year.

Clustra recently debuted a packaged data management solution called Clustra Parallel Data Server 3.0. While it offers high availability and scalability, Clustra officials say the relational database management system's (RDBMS) biggest selling point is its ability to offer the five nines of reliability.

Five nines is a term used to denote 99.999 percent uptime with database services or online applications. When it comes to managing high availability and downtime, the database is one of the main problem points in a system.

Clustra's solution to this problem is ensuring the database doesn't go down. "What you need to do is build high availability and scalability into the system," says Gary Ebersole, senior vice president of sales and marketing at Clustra (

Clustra ensures its five nines policy by dividing data into fragments that are stored in eight nodes and two units. The two units can run side-by-side or, preferably, each one in a separate location. The units are linked via a redundant communication network. A copy of each node is made so a company's entire database has an exact replica of the original. The original data is stored in "primary" fragments, while the replicated data is saved in "standby" fragments. The primary and standby fragments are then stored in a node. Each node contains a primary and standby fragment.

If one node or one fragment goes down, the replicated node kicks in seamlessly so that downtime is less than a few seconds, which is unnoticeable to the user. If an entire node goes down, Parallel Database makes a copy of the whole node and moves it to one of the two spare nodes that are reserved for such an instance.

"The solution also has built in self-repair. It can handle a failure, keep running, and repair the database while running nonstop," Ebersole says.

If you need to add nodes, the system scales linearly. A user can add pairs of nodes when needed and can do so without shutting the database down. "You never have to shut the database down to do an upgrade, and once you tell the cluster you are going to take it down, the applications running have no idea," Ebersole says. As long as you tell the cluster you are going to take it down or add nodes, it will tell the database to refragment itself across the nodes.

Clustra Parallel Database Server usually runs in lieu of other database systems, such as SQL Server 7.0 or Oracle8i, but it can run alongside other databases, since a company rarely employs a single database for all its needs.

Potential users may wonder if any additional security issues are incurred because the system holds two copies of the data. "We don't see any incremental security issues, since these databases are normally behind a firewall in a secure environment. It's no less secure than any other database system," Ebersole says.

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