Glossary of Terms: Fault Tolerance
Definition: Fault tolerance is a level of protection in a computing environment used for mission-critical applications that require >99.999% availability and RTO and RPO of near zero. Fault tolerant systems require an investment in redundant hardware, software, networking and other systems. In these environments, two or more systems operate synchronously – performing compute functions simultaneously, so that in the event of a hardware, software, or network failure, application operation will continue without interruption or dropped transactions.
Reproduced from SIOS