Continuing to put pressure on rival disk interface standards, IBM Corp has announced adaptor boards that make it easier for OEM customers to build storage products that implement Serial Storage Architecture. The boards have been designed to enable Serial Storage disk drives or subsystems to be attached to personal computers, workstations and servers with Peripheral Component Interconnect buses. The IBM SSA Adapter for PCI Model PNS4-20 supports two Serial Storage Architecture loops with a data transfer rate of up to 160Mbps and more than 3,000 input-output request commands per second. It will support up to 96 devices, considerably more than can be achieved using SCSI. It uses the SCSI-2 command set, which IBM says eases migration. The PNS4-20 attaches to multiple operating systems and hardware systems and will be available initially with OS/2 and NetWare device drivers, with AIX, Windows NT and Santa Cruz Unix drivers later. The IBM SSA RAID Adapter for PCI, Model PRS4-20 provides RAID levels 0, 1, 3 and 5 functions. It also supports two Serial Storage Architecture loops and will provide a data transfer rate of up to 160Mbps and more than 1,000 RAID 5 input-output commands per second. The board will support up to 96 devices and will again come first with OS/2 and NetWare device drivers, with the others listed to follow. IBM hopes designers will opt for its Ultrastar XP 2.0Gb and 4.0Gb disk drives that have Serial Storage Architecture interfaces, but they work with any Serial Storage device. And IBM will make available adaptor kits for manufacturers interested in evaluating integration of the adaptors. Kits include an IBM SSA PCI Adapter or PCI RAID Adapter, an Ultrastar XP 4.0Gb disk, a Serial Storage Architecture cable (no-one manages to charge more for cables than IBM), and device drivers and utilities. In March IBM made engineering details of the Architecture available to other manufacturers to encourage design of chips for the technology, with a free right to use this information subject to patent rights (CI No 2,628). IBM also plans to license some patents that cover the interface which are needed to implement it. The main rival to Serial Storage Architecture is Fibre Channel Arbitrated Loop, but IBM reckons the former is less costly, has higher reliability, provides an easier migration path for systems currently operating with SCSI, and is available today in adaptors and is supported by multiple suppliers. Serial Storage Architecture is capable of concurrent transfer for data at high speeds between many pairs of serially connected peripherals, without the need to route the data through the processor. And the interface is compatible with the Fiber Channel Interface which enables interconnection of processors separated by large distances. The adaptor boards and kits will be available in OEM evaluation units either this month or next. The PNS4-20 IBM PCI Non-RAID Adapter Card is available now, at $750, as is the PNS4-20 SSA Non-RAID Adapter Kit at $2,500. The PRS4-20 SSA PCI RAID Adapter Card will cost $1,200, the PRS4-20 SSA PCI RAID Adapter Kit $5,500 and both will be out next month.
