Indie Film Backup on a Shoestring: Cost-Effective Strategies & DIY Checksums?

Hey fellow filmmakers, Tyler Morrison here. I'm operating on an indie feature right now (shooting primarily on an AMIRA with some C70 B-cam work) and our budget is incredibly tight. We've got enough for all the essential gear, batteries, and the cards themselves, but when it comes to post-shoot data management, we're really scraping by.

My usual workflow for larger gigs involves LTO and robust cloud solutions, but those are completely out of reach here. We're currently just copying cards to two separate external drives on set, then those drives go to the editor. I'm constantly paranoid about data integrity with this minimal setup.

Has anyone found genuinely reliable, absolute minimum cost backup strategies for footage? Specifically, I'm wondering if there are any clever, free or very low-cost DIY methods for checksum verification or anything beyond just drag-and-drop copies to ensure those files are solid? Any advice from the trenches would be massively appreciated!