Here is a zope configuration example:

    <zodb>
      <loggerstorage>
        <filestorage>
          path data.fs
        </filestorage>
      </loggerstorage>
    </zodb>

- do dependency between steps only based on tags. This avoid having hardcoded
list of method ids that are not friendly with further extension
- add a mode to force doing the upgrade. Doing fully upgrade based on previous
sense() is not acceptable. For example we might be in a case of broken catalog
that does not support any new insertion until upgrade is finished