To ensure reliability, some file systems and databases provide support for something known as journalling. The idea is to ensure data consistency by creating a log of actions to be taken (called a Write Ahead Log) before committing them to disk. That way, if a transaction were to fail, the write ahead log could be used to finish writing the data.

While this functionality is often available with full-fledged databases, often it is not completely necessary, yet reliability can be desirable. Other times, the filesystem does not provide support for journalling, but it can still be desirable. Thankfully, Alberto Bertogli published a userspace C library called libjio that can provide these features in a small (less than 1500 lines of code) library with no external dependencies.