IBM is set to unveil an update to its high-end z990 mainframe that analysts say will enhance the system's reliability and security and bring as much as a 40% performance boost to a product that is aimed at corporate users running very large database and transactional systems.

The official announcement is expected at an IBM event in New York on Tuesday that is being hosted by Bill Zeitler, senior vice president and group executive of IBM's systems group. An IBM spokesman declined to comment, except to say that the event is "bigger than the mainframe."

Industry observers expect the event to focus on IBM's larger on-demand and virtualization strategy, where the mainframe will play a key role.

"IBM continues to try to make the mainframe the center of the on-demand data center and they're going to enhance the things they think are required in that area: security and availability, plus providing more flexibility," says John Phelps, an analyst at Gartner.

"Their challenge is to be able to enhance it such that it can draw in other platforms and work with them," he says.

Analysts also expect the new machines to be bigger and faster. The system will be built on engines running at 600 MIPS, analysts say. The z990 has engines running at about 450 MIPS.

In addition, while the new system isn't expected to have more processors, end users will be able to allocate more of them to workloads so that the system can scale up to a 38-way machine. The z990 scales to a 32-way configuration because some of the processors are allocated strictly for spares or system-assist functions.

During a conference call with analysts following the release of IBM's second-quarter financial results last week, IBM CFO Mark Loughridge said that a new zSeries will be announced this week, "with availability in September." He said that integration, security and workload management features will be enhanced in the new mainframe.

After double-digit growth in 2004, zSeries revenue has taken a hit. Revenue declined 24% during the second quarter, compared with the same quarter a year ago, caused in large part by customers awaiting the new product announcement, Loughridge said.

At the same time, workloads running on the mainframe are expanding. "About 60% to 70% of our revenue is associated with new workloads, particularly Linux, enterprise applications and WebSphere," Loughridge said.