Ultra160 SCSI - Page 1

Source: Maxtor

- Introduction

On September 14, 1998, seven vendors, representing a broad cross-section of the computer system and storage industry, announced support for evolutionary changes to the Small Computer System Interface (SCSI) that increase performance, reliability, and manageability. Ultra160 SCSI doubles transfer rates from 80 to 160 Megabytes per second, improves manageability by automatically testing the interface’s performance level and increases reliability by adding Cyclical Redundancy Checks (CRC). When Ultra160 SCSI is used with low-voltage differential (LVD) signaling, cable lengths of 12 meters are maintained providing full backward compatibility.

The SCSI technology continues to evolve and its evolution is successfully meeting the increasing demand for I/O bandwidth. The SCSI interface has the stability, ease of connectivity, large installed base and a 15 year heritage offering full backward compatibility. The new implementation of SCSI boosts performance, reliability, and manageability even more.

- What is Ultra160 SCSI?

The ANSI standards T10 committee is revising the SCSI Parallel Interface (SPI-3). This document is the basis of the Ultra160 SCSI technology. Evolutionary changes have been made to the existing SCSI protocol (SPI-2) to increase performance, manageability, and reliability. All changes are incremental, and existing SCSI protocols are maintained for backward compatibility. Three new underlying components of Ultra160 SCSI are Double Transition Clocking, Cyclical Redundancy Checks (CRC), and Domain Validation.

- What technology Enables Ultra160 SCSI?

Ultra160 SCSI doubles transfer rates to 160 Megabytes per second by using both edges of the request/acknowledge signal to clock data. This creative solution provides designers with the choice of improving speed, reliability or connectivity. It allows system designers to choose bus bandwidths up to 160 MB/second using existing Ultra2 SCSI cable plants. Alternatively, this technology lets designers maintain Ultra2 SCSI speeds (80 MB/second) and improve reliability by lowering clock speed, allowing more margin for ASICs and cables.

Other Ultra160 SCSI improvements include automatic tests of the interface’s performance level for increased manageability and the addition of CRC for reliable data transmission. When Ultra160 SCSI is used with LVD signaling, cable lengths of 12 meters are maintained providing full backward compatibility.