fault tolerant


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fault tolerant

fault tolerant

The ability to continue non-stop when a hardware failure occurs. A fault-tolerant system is designed from the ground up for reliability by building multiples of all critical components, such as CPUs, memories, disks and power supplies into the same computer. In the event one component fails, another takes over without skipping a beat.

Tandem and Stratus were the first two manufacturers that were dedicated to building fault-tolerant computer systems for the transaction processing (OLTP) market.

High Availability
Many systems are designed to recover from a failure by detecting the failed component and switching to another computer system. These systems, although sometimes called fault tolerant, are more widely known as "high availability" systems, requiring that the software resubmits the job when the second system is available.

Redundant Hardware
True fault tolerant systems with redundant hardware are the most costly because the additional components add to the overall system cost. However, fault tolerant systems provide the same processing capacity after a failure as before, whereas high availability systems often provide reduced capacity. See fault management.


A RAID Array
This RAID II prototype in 1992, which embodies principles of high performance and fault tolerance, was designed and built by University of Berkeley graduate students. Housing 36 320MB disk drives, its total storage was less than the disk drive in the cheapest PC only six years later. (Image courtesy of The Computer History Museum, www.computerhistory.org) See RAID.







Redundancy
Redundancy is the hallmark of fault tolerant systems. This storage server from Xtore Extreme Storage (www.xtore-es.com) contains multiple, hot-swappable power supplies to ensure continued operation.
References in periodicals archive ?
NECSAM will be offering its existing fault tolerant customers a promotional program to upgrade to the Express5800/320Ma FT server.
NEC's Fault Tolerant solutions are the perfect complement to Softricity's SoftGrid application management platform," said Larry Sheffield, Senior Vice President of the Solutions Platform Group for NEC Solutions America.
NEC Solutions America will work with independent software vendor (ISV) partners to certify their offerings for the SoftGrid solution, enabling customers to ensure their applications are fault tolerant ready.
When a fault occurs at the server, the software understands that the server is designed with fault tolerant hardware.
The Best of Show Award follows the March 2003 launch of the NEC Express5800/320Lb, the company's second-generation continuous availability, fault tolerant server.
As one of many prestigious industry awards received by NEC Solutions' fault tolerant server series, the Windows & .
The Express5800 fault tolerant and general purpose servers are available immediately from NEC Solutions America.
Complimenting its fault tolerant server line, the company expects its 32-way Intel Itanium 2-based Express5800/1000 server series to be added to the GSA contract soon.
When compared with the equipment, software, professional services, and maintenance costs of clustered servers, the fault tolerant systems are less expensive to implement and operate; and they provide higher levels of availability in almost every case.