What Does Versioning File System Mean?
A versioning file system is a type of file system which stores copies of a file at various points in time, rather than simply overwriting changes. Thus it is a kind of revision system which lets the user access the older versions or copies of a file as it appeared at any point in time. As soon as a new copy is made, the older ones are saved in the local disk of the system.
Techopedia Explains Versioning File System
A versioning file system is useful for revision control, but should not be confused with a backup system because the older versions of a file are not archived. As the file is open for reading/writing, the file system automatically saves a new instance of that file. The name of file is appended with an updated version number, starting from 1 onwards. When a file is fetched and opened, the most recent version number instance is opened for the user. Similarly, the user can specify any of the older versions to be opened.