:(DELETE) This text describes "product name", is not an encyclopedic entry. In

computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, e ...

, System Fault Tolerance (SFT) is a

fault tolerant system Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of one or more faults within some of its components. If its operating quality decreases at all, the decrease is proportional to the ...

built into

NetWare NetWare is a discontinued computer network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, using the IPX network protocol. The original NetWare product in 19 ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

s. Three levels of fault tolerance exist: * SFT I 'Hot Fix' maps out bad disk blocks on the file system level to help ensure data integrity (fault tolerance on the disk-block level) * SFT II provides a

disk mirroring In data storage, disk mirroring is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. It is most commonly used in RAID 1. A mirrored volume is a complete logical representat ...

or duplexing system based on

RAID Raid, RAID or Raids may refer to: Attack * Raid (military), a sudden attack behind the enemy's lines without the intention of holding ground * Corporate raid, a type of hostile takeover in business * Panty raid, a prankish raid by male college ...

1; mirroring refers to two disk drives holding the same data, duplexing uses two data channels/controllers to connect the disks (fault tolerance on the disk level and optionally on the data-channel level). * SFT III is a server

duplexing A duplex communication system is a Point-to-point (telecommunications), point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many commu ...

scheme where if a

server Server may refer to: Computing *Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients Role * Waiting staff, those who work at a restaurant or a bar attending customers and su ...

fails, a constantly synchronized server seamlessly takes its place (fault tolerance on the system level).

References

Novell NetWare 4.2 documentation
Novell NetWare {{comp-sci-stub