Multi-tenant backup solution
 

Is there an open-source multi-tenant backup solution so I can set up a backup-server somewhere in a data centre and let multiple customers make use of it ?

So they have there own space and can control there own documents.

According to this, zmanda has a GUI http://www.zmanda.com/blogs/?p=44
http://www.zmanda.com/ZMC-Quick-Tour...Tour-Demo.html

Could you describe your environment a bit more? Are you setting up virtual hosting? By that I mean some kind of virtual environment, containers, ldoms, whatever terminology your choice of tools might use? Zmanda also has a virtual appliance configuration for Amanda. If you want your tenants separated, that sort of solution might work. Otherwise you get into a situation of multiple people having admin capability and possibly interfering with one another.

Well, actually you could see it as SaaS. I already have hosted groupware, hosted VOIP and would now like also hosted backup.

Every solution is hosted on a Xen vm.

Hard to tell whether this suits your needs, but -- http://www.businesswire.com/portal/s...48&newsLang=en