I keep multiple versions as well, and also use third-party backup software on all these files. These techniques are meant to be part of something analogous to a 'defense in depth' against errors in the backup process, not thorough or foolproof.
> Not only do you have to validate a file looks like a .jpg/.json/.zip file, you also need to validate that it looks semantically correct (ie. the file format is valid but a chunk of it is missing).
But you don't have to do that perfectly to get value out of it; for example:
- If the .json file parses as json, then at least you probably didn't truncate the download mid-stream.
- If it also contains a particular attribute, then you probably didn't save a structured error response instead of the actual data, or save something from a radically-nonpassively-changed endpoint that might no longer be adequate.
- If it also has roughly the number of elements you expect, you probably didn't miss entire pages of the response.
