Obviously, I do not understand the term "to mount a nonundoing storage". Does that mean "to mount a storage system, such as SQL table, inside ZODB, so that it behaves transparently as part of ZODB tree"?
No. A "storage" is a ZODB concept which means a literal Python object that implements the Storage interface. "Nonundoing" means that the storage doesn't support undo operataions (ala the Zope Undo tab). The doc means "mount another ZODB storage that is nonundoing".
Can you give some URLs where I would learn about that
Sure. http://www.zope.org/Members/mcdonc/HowTos/UseExternalMountWithCST -- Chris McDonough Zope Corporation http://www.zope.org http://www.zope.com "Killing hundreds of birds with thousands of stones"