[Zope] Zope admin/backup question

Backing up Data.fs everynight--- is it in a usable state if it is backed up while Zope is running? I haven't actually tested the restored Data.fs yet, I wanted to get some feedback first. Also, are the Data.fs.in and Data.fs.lock files necessary for restore or 'moving' a Zope install? I have already just moved the Data.fs file over to a virgin Zope install and it seems to be working OK. -andy diller