At Weta we divided up the NFS servers into "src" and "dat" - "src" was everything made by artists, and "dat" was the output from the renderwall. We backed up "s

At Weta we divided up the NFS servers into "src" and "dat" - "src" was everything made by artists, and "dat" was the output from the renderwall. We backed up "src" every night, but "dat" was never backed up. Every once in a while there would be some mass deletion event but it was always faster to re-render the lost data than to restore from backups. Also none of the high end commercial filers are single node - they're all clusters of varying sizes.