[Zope] Zope file system and scalability

Dear friends, Greetings! I am trying to build a huge extranet using zope where there will be large amount of messageing and file shareing. How scalable is Zope object file system. I was told zope has to keep complete zope data.fs in memory so as to work. Is this true. Are there any further reference articles on this. As part of the project i need to enable users to upload the work files such as StarOffice clac files, word documents and pdf. If they use to file object in zope then the file gets embedded to zope data.fs making it enormously huge. Is this preferable. or should i try loacl fs. Any help in this will be of immence value. Regards, - sree