I'm researching ways to backup FCPX projects for longterm. As I see it there are files in a FCPX project that can be deleted because FCPX generates these files anew, when they are not present. Peak Data and Transcoded Media specifically.
Is there anything else we can delete from projects safely?
Don't mess with the bundle. Deleting generated files will accomplish the same thing without corrupting your library.
But I think the better solution is to create a new library using just the media you want. For example, when I'm done with a project, I select the project(s) in the browser and choose File>copy project to library>new library. This will copy only the files used in that project. So all the stuff you logged that you didn't use in the project will be omitted.
Once you have your new library, open up the library prefs pane in the inspector and choose to consolidate all the media. I'd suggest to consolidate it internally, and not to an external folder. This keeps the library as a perfect single unit that can be transported or moved without ever risking losing the media or breaking media links. You can always consolidate it again to an external folder at a later date if that works better for your style or multi-user editing setup or what not.
The beautiful thing with all this is that if you do all this to the same drive as the original library/media, it will not take up any additional space on that drive. All the links are hard links to the media (not the files) themselves. They're not aliases. The files can exist in multiple places at once but only take up the space of one file. You can delete the original or the new library and it won't harm the other. The shared media will not be deleted until all hard links to it are deleted.
Give it a try. Since the media doesn't actually get copied, it'll only take seconds to duplicate a library that might be hundreds of gigs.
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