The ArchiveMode controls which revisions are kept to build the PageHistory. Usually it is not desirable to keep each single revision, because of (1) the large storage requirements and (2) because the PageArchive then becomes difficult to survey.
In general ArchiveMode=3 is recommended (maybe tuned): it is space efficient and gives reasonable security to single users working on their pages.
- ArchiveMode=0 (no RCS archiving is done, there is still the version of the previous author, not recommended)
- ArchiveMode=1 (RCS snapshots are done when the Author changes only, recommended for communities of experienced users, not recommended for PersonalWikis)
- ArchiveMode=2 (each single change is archived, automatically used for all ContextPages, recommended for newcomers)
- ArchiveMode=3 (a compromise, works like ArchiveMode=1 taking snapshops when the author changes, but also takes snapshots when some limits are exceeded, recommended in general)