System Fault Tolerance (SFT) is a fault tolerant system built into Netware operating systems. There are three levels of fault tolerance:
- SFT I 'Hot Fix' maps out bad disk blocks on the file system level to help ensure data integrity (fault tolerance on disk block level)
- SFT II is a disk mirroring or duplexing system based on RAID 1; mirroring refers to two disk drives holding the same data, duplexing uses two data channels/controllers to connect the disks (fault tolerance on disk and optionally data channel level).
- SFT III is a server duplexing scheme where if a server fails, a constantly synchronized server seamlessly takes its place (fault tolerance on system level).
Novell Netware 4.2 documentation