System_Prevalence
System prevalence[1] is a simple software architectural pattern that combines system images (snapshots) and transaction journaling to provide speed, performance scalability, transparent persistence and transparent live mirroring of computer system state.
In a prevalent system, state is kept in memory in native format, all transactions are journaled and System images are regularly saved to disk.
System images and transaction journals can be stored in language-specific serialization format for speed or in portable formats for cross-language consumption.
The first usage of the term and generic, publicly available implementation of a system prevalence layer was Prevayler, written for Java by Klaus Wuestefeld in 2001.[2]