Never-Say-Die Database Targets Web Sites

BURLINGTON, MASS. (03/17/2000) - Clustra Systems, a spinoff of Norwegian telco Telenor, initially built its high-performance database for the telecommunications industry. But the company is aiming its latest version at high-volume Web sites.

The Clustra Parallel Data Server 3.0 is designed to stay up and running even in the event of computer or network outages. In effect, the software makes a copy of the data, fragments the original and the copy, and then spreads them across scores of processors, each with its own memory and disk storage. If any processor fails, the server can rebuild the data on a spare one.

This "shared nothing" architecture means that the failure of any one processor only affects a small portion of the data in the database, which continues to run as it rebuilds the affected data on a different processor.

Clustra's software originally was used by telecom providers for such tasks as high-speed, high-volume directory lookups. But Clustra figures the software is also a good fit for Web sites, where systems failures can lead to big losses in revenue and customer satisfaction. Today, the job of building a fault-tolerant Web site is laborious, says Gary Ebersole, a senior vice president at Clustra.

Companies typically need to piece together special computers and database versions as well as third-party clustering and cluster management software, he says.

"Our server was designed from the outset for less than 2 minutes of downtime per year, whether planned or unplanned," Ebersole says.

Clustra guarantees that if the server goes down in a given month, the customer doesn't have to pay that month's licensing fee.

Other database vendors have taken a different approach. Informix, for example, offers an entirely separate database product for high-availability applications, Ebersole says. In any case, none of Clustra's competitors will claim 99.999% uptime and guarantee it, he says.

Clustra runs on low-cost Intel-based computers, which can be rack-mounted.

Currently, the software runs on Linux, Windows NT 4.0 or FreeBSD, a Unix variant. With this approach, "the operating system itself doesn't have to scale, we do that," Ebersole says.

With most Web sites, companies add more Web or application servers to handle larger loads. But the traditional databases behind the Web site can't scale so easily, and adding more disks or processors often means taking the entire database offline.

By contrast, Clustra administrators simply plug in new rack-mounted computers and additional disk arrays, and load a new instance of the database. One drawback is that application developers must use Clustra's native API instead of the standard SQL '92 interface. Ebersole insists the programming is "completely transparent" to the developers, but Clustra will add SQL '92 support with Release 4.0 in September.

Near year-end, Clustra will add the ability to replicate data among Clustra servers at different sites. By June, programmers will be able to use Java to write database-stored procedures, which are like small applications stored in the database.

Clustra's software is available now. Pricing starts at $75,000 for a four-node license on Intel processors. Eventually, the software will be ported to RISC computers running Solaris and HP-UX.


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