At the hardware level, distributed systems have incorporated industry-standard versions of technologies with mainframe roots, such as Fibre Channel, InfiniBand and IBM's Chipkill error-correction technology, which is used in memory for high-availability systems. "Every big server now has dynamic partitioning, a channel architecture -- things like InfiniBand -- and they all have 64-bit support and large memory," says John Abbott, an analyst at The 451 Group in New York. While IBM says proprietary channel architectures such as Ficon and Escon have advantages, Bank of New York's Mulligan would rather have standardized I/O. "An imaging application we have and a storage device we'd like to leverage are not supported cleanly by IBM's Ficon architecture," he says. "You end up buying these esoteric boxes that emulate the protocols."

But for MIB Group's I/O-intensive application, channel performance is more important than using open-standards hardware. Today, InfiniBand can't drive the number of concurrent channels DiAngelo needs. "We need that back-end channel capacity, and that's something the mainframe does very well," he says.

Still, proprietary I/O hardware is costly. "You pay a hell of a lot to get those channels in place," Abbott says. Most mainframe applications would do just as well with InfiniBand and off-the-shelf adapters, he adds.

That's the direction that IBM is moving in, says Guru Rao, an IBM fellow and chief engineer for the eServer line. While the mainframe is the system most capable of handling complex environments, he says, "a high-value system cannot provide only unique technologies. It has to be able to exploit and leverage high-volume capabilities in the industry." IBM already offers some support for Fibre Channel, and the next-generation mainframe will also support InfiniBand, Rao says. That evolution to support standards-based, commodity hardware architectures is necessary if IBM is to narrow the price gap separating the mainframe and distributed systems.

Mainframe vendors have also struggled with proprietary processor designs, which can't compete on price with high-volume Intel chips. The IBM plug-compatible mainframe market all but disappeared as the costs of keeping up soared. Bull and Unisys have both thrown their lot in with Intel (although Unisys says it will continue to offer some designs of its own), but IBM is taking a middle road. Its Power architecture is used in gaming systems, and IBM says it plans to leverage the economies of scale generated from those volume products to develop a more competitive, "higher value" version of the Power5 for the mainframe. "We are going to provide the same benefit to the mainframe ... as we have for the iSeries," Rao says. The zSeries processor will include "elements of the Power5 architecture," but the chip set will remain unique, he adds. IBM's efforts are bringing costs down by about 20 percent per year, says Abbott. However, the price/performance improvements for x86-based systems have been in the 30 percent to 45 percent range, he says.