How should we back-up our media files for our production studio
My process is always to start from the recording media, move the files from recording media to a 12TB external RAID5 array with a utility that verifies the integrity of the transfer.  This is my long term working archive.  

While I don't do this at this time, I'd recommend making periodic off-site backups of this array (either to a cloned array or to tape) to guard against loss of the entire RAID array.

For actually working with the assets, I copy (not move) the files to an internal scratch SSD RAID0 array.  Upon completion or archiving of a project, I move only the project files and any newly created files that need to be stored to the RAID5 archive.  I then rename my scratch folder, verify the project works when loaded on the archive array and then delete the renamed folder (which should only contain copies of the master source files.)

This protects against any corruption of original source files while editing and also minimizes the amount of data that I have to move off of the scratch disk.