Ultra160 SCSI - Page 3
- 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
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
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.