I am replacing an old Linux file server serving NFS and CIFS. For the new server (still serving CIFS and NFS), I would like to have software that automatically and efficiently maintains old revisions of files in parallel trees, so that they can be accessed by users without special tools. I am looking for software that is akin to Time Machine or Flyback, but works well on a server.
The dataset is some 10000 files weighing maybe 60 GB. Changes are relatively few, usually less than 100 files changes daily.
Using LVM snapshots will not cut it, as the old revisions must reside on a separate set of disks from the live data.
Edit: To clarify: keeping old revisions is non-vital addition to the solution, so any suggestion will have to stay in the range of some hundred euros.