This paper proposes a survey of software fault-tolerant clock algorithms:deterministic, probabilistic and statistical, and also give a analyzing of these three kind of algorithms.

Fault tolerance can be provided by redundancy — redundant disks, computers, and even data centers — but it is transactions that make it practical to build fault-tolerant software applications.

Server makers pride themselves on their high-end machines' ability to withstand failures, but Google prefers to invest its money in fault-tolerant software.