3-2-1 backup on set: applying the rule to camera media
The 3-2-1 rule is the backup world’s oldest good idea: three copies of your data, on two different media, with one kept off-site. It was written for IT, but it maps cleanly onto a film set — where the “data” is footage that can’t be reshot. Here’s the set version.
Three copies
The camera card is copy one — but it’s the copy you’re about to erase, so it doesn’t count for long. On set, “three copies” usually means the original plus at least two you make during offload: a master drive and a shuttle. More on a big day. The card only gets wiped once those copies exist and are verified.
Two different media
Two copies on one physical drive is one failure away from zero. “Two media” means two separate physical drives — ideally different makes or ages, so a bad batch doesn’t take both. This is why a real offload tool distinguishes “two folders” from “two drives,” and why it should refuse to call a card safe until the copies are on genuinely separate hardware.
One off-site
The off-site copy is the one that survives a stolen cart, a fire, a flooded hotel room. On set that’s usually the shuttle drive that leaves with the courier or the producer, separate from the master that stays. It doesn’t have to be far — just not in the same bag as everything else.
The part 3-2-1 doesn’t say: verify
Copies you didn’t verify aren’t backups, they’re hopes. Every copy in your 3-2-1 should be checked by reading it back off the disk and comparing checksums, with the result recorded in an ASC MHL manifest and your offload report. Only then is the card safe to format. (How do you know a card copied correctly?)
Doing it in one pass
Olycen is built for this: it reads the card once and writes to every destination at the same time, verifies each file on every drive, and offers the card for formatting only when every file is verified on at least two physical drives — your master and your shuttle. 3-2-1, proven, before the card is wiped.
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Keep reading: How to offload an SD card to multiple drives on Mac · What is a DIT report?
Offload that never lies to you.
Olycen copies every card to as many drives as you want, verifies each file by reading it back, and only says the word verified once the proof is in. One-time $129, two Macs, no subscription — the launch list pays $99.