Create a new Zope instance. Perform some changes and then pack the database to remove objects revisions older to 0 days. You want a clean instance to start with.

Now create a cron job to daily pack the database to remove objects older to 14 days, and start to use your instance. Zope won't pack the database at all, and I guess it will be for the first 2 weeks, because it won't find revisions older to 14 days during that time.

Is that normal behaviour? Telling by the interface text at the Database Management tab, it looks like the command would create a Data.fs.old file even though there weren't older revisions than the number set, meaning that by default the packing would create an exact copy of the current Data.fs (to keep all changes), at least until there were revisions to remove. The problem is that if you rely on Data.fs.old for backup purposes, you'll find that your 13th day Data.fs.old is exactly as that of day one.

An even though you had never packed the database to 0 days, the problem would come up if, for any reason, you feel like it's time to manually pack the database to 0, in between those two weeks. Your cron job won't modify the existing Data.fs.old for the following two weeks.