HP will start shipping Itanium-based Integrity NonStop servers in July, but it plans to continue selling its existing MIPS-based systems until 2008, the company has announced.

HP will support the MIPS-based NonStop systems until 2013, expecting that customers will operate both systems side by side.

"A lot of customers will have co-existence for a long time," said server product manager Randy Meyer. The Integrity NonStop system can scale up to more than 4,000 Intel Itanium 2 processors.

NonStop servers are fault-tolerant, built up to triple redundancy, and are commonly used in high-transaction processing environments, especially financial services. HP has been talking about a migration to Itanium for the past several years and has been preparing the way for the change. HP solidified the arrival of this product set last December, when it promised the servers as part of its announcement of $3 billion investment in Itanium-based products.

About 90 per cent of NonStop's top independent software vendors have applications ready for the Itanium-based system, HP said. Users moving applications to the new system will need to recompile the software.

This isn't the first time that NonStop users have made a platform switch. About a decade ago, users moved from CISC-based chips to MIPS-based systems. Because of that, analyst Richard Partridge from Ideas International Group said the switch to Itanium "isn't a traumatic move that is going to change everything. NonStop users know it can happen without distraction."

The Itanium chip will bring a performance gain, Partridge said, something users will need because of increasing demands on their systems. He also said he doubts users will use the coming migration to dump NonStop for alternative systems, such as clusters with rapid fail-over capabilities. That's because users of these systems can't afford a lost transaction, he said.

Stratus, specialist in high availability servers, may also stand to gain.