Log Message:
DirectoryStorage is a Storage for ZODB, the object database used by Zope. It
uses ordinary files and directories to store revisions of ZODB objects; one
file per revision per object.

The following features differentiate DirectoryStorage from other storages:
 * A very simple file format; one file per revision per object. Your data is
   not locked away inside an unfamiliar, opaque database.
 * Designed for disaster-preparedness. Restore service after a disaster faster
   and with greater confidence.
 * Storage Replication. Efficiently and robustly keep an online backup copy of
   your storage up to date with the latest changes from the master.
 * Designed for fault tolerance. Any bugs (in DirectoryStorage, or elsewhere)
   are less likely to irretrievably destroy your data.
 * Many more.