Ultra160 SCSI - Page 3

Source: Maxtor

- Cyclical Redundancy Checks (CRC)

The Ultra160 SCSI reliability enhancements include the addition of a Cyclical Redundancy Check on customer data. CRC provides extra data protection for marginal cable plants, external devices, and is one of the best ways to assure data protection during hot plugging. CRC offers higher levels of data reliability by ensuring complete integrity of transferred data. It dramatically reduces undetected error rates by using the same proven CRC that is utilized by FDDI, Ethernet, and Fibre Channel interface.

The Ultra3 SCSI CRC detects:
All single bit errors
All double bit errors,
All odd number of errors
All burst errors up to 32-bits long
And has a ~2-32 rate of undetected random error patterns
Domain Validation

The third component of Ultra160 SCSI is Domain Validation. This technology intelligently tests storage networks including cables, backplanes, terminators, expanders, bridges etc. Domain Validation ensures that the network is operating at the required specifications. If reliability is at risk, the transfer proceeds without a hitch at a lower speed—much the way today's modem and fax transmissions connect despite variations in equipment. Domain Validation should increase end-user satisfaction and decreases total cost of ownership by reducing service calls for under performing systems. In addition these tests could save on call center support resources and help alleviate end-user frustration.

In the past new devices such as HBAs (host bus adapters) and HDDs (hard disk drives) did not always work smoothly with legacy configurations. Domain Validation helps assure that Ultra160 SCSI devices operate smoothly in existing legacy systems. This testing is done auto-matically without changing controller settings, setting BIOS parameters, or fumbling with manuals.

- Ultra160 SCSI: The Need for Speed

The rule of thumb for the past 15 years has been that bus bandwidth should be at least 4 times the maximum throughput of a drive. The Ultra160 SCSI bus bandwidth should stay comfortably ahead of the internal transfer rates of the next generation 10K HDDs expected in 1999. These HDDs can saturate the Ultra2 SCSI bus with as few as three drives.

SCSI has a 15-year heritage of maintaining full backward compatibility and excellent forward compatibility. About every two years small evolutionary changes are made to this standard to improve speed, reliability and manageability. The low risk upgrade to Ultra160 SCSI is the next natural transition to protect your investment. The implementation of Ultra160 SCSI should give customers peace of mind because the changes are mostly digital and straightforward to simulate and implement.

- Summary

These new interface improvements address the most critical requirements in data storage environments. Ultra3 SCSI provides fast data delivery and is both a simple and cost effective solution for system OEMs to implement. From a system designer’s perspective, the big benefit of the new interface is the flexibility it offers to readily optimize a platform for a particular market. It enables end users to continue capitalizing on the low-cost connectivity advantages of the SCSI interface. Ultra160 SCSI maintains complete backward compatibility with all earlier SCSI systems.