HP applies crossbar switching to network storage

Crossbar switching, which replaces conventional bus-based technology, reportedly will double or even triple the speed of disk storage arrays. Hewlett-Packard said its storage system, the XP512, also allows service providers to support multiple companies, because the crossbar provides dedicated bandwidths for different applications. "You can't do that with a bus-based system," said David Scott, general manager of Hewlett-Packard's Extended Platform Storage Organization (Palo Alto, Calif.).

"When you have different applications sharing the same bandwidth, you run the risk of one company's application severely impacting another company's application. With crossbar switching, you don't have that problem because each application has guaranteed bandwidth."

Hewlett-Packard executives said that the XP512 will offer sequential I/O performance of 840 Mbytes/second and random I/O performance of 31,000 I/Os per second. In contrast, competing bus-based systems now offer 340 to 350 Mbytes/s and 10,000 to 15,000 I/Os per second, they said. "In terms of I/O performance, they are significantly ahead," said James Opfer, senior analyst for server storage and RAID at Dataquest Inc. (San Jose, Calif.). "That's one way these systems will distinguish themselves."

Scalable storage

The XP512 will be used mainly by enterprise IT organizations and service providers, including Internet and storage service. It scales up to 512 disks and 24 Tbytes of data. Used in switched storage-area network configurations, the XP512 offers up to 928 host connects.

The system's real technical advance, however, is its use of crossbar switching. Crossbar switching, in which electromagnetic switches link front-end server connections to back-end disk arrays, allows each application to have its own dedicated bandwidth. In that sense, it contrasts sharply with bus-based systems, in which applications share bandwidth.

Crossbar technology has recently become popular in the server domain, where it has overtaken conventional bus-based technology. "Just as it did in servers, the crossbar switch will obsolete bus-based architectures in high-end enterprise storage," Scott predicted.

HP became the second company to introduce the crossbar switch to network storage. Hitachi Data Systems did the same in the past month. Both companies use crossbar switches from Hitachi in their storage systems.

HP said its product is distinct from Hitachi's in its use of software management tools. A graphical interface program manages the storage arrays, and another program reports errors that occur in the array, on disks or elsewhere. "It allows administrators to very rapidly identify what has gone wrong and take corrective action," Scott said.

HP also announced that it will support Sun Solaris environments along with HP-UX, Linux and Windows NT in storage consolidation applications.