Data Recovery Case File · Cameras, Drones & Cards · A Day's Work on One Card
Full and Empty Are Read From Different Places
Her enquiry describes two contradictory readings a day apart. Filming professionally all day, "the card I was using said full so I removed it. Today, when checking the files on my laptop, there was an error message and now the card is empty, as if it has been formatted — I have not manually formatted it or done anything to it since filming." Those two reports are not in conflict — free space and the file listing come from different structures, and damage to one explains both.
| Media | SD card holding a full day of professional video — reporting no remaining capacity during use; presenting no files subsequently; no format performed by the owner |
| Reported situation | Card in professional use throughout a day of filming · camera reporting the card as full · card removed and set aside · error reported when accessed on a computer the following day · card presenting as empty · no format or other action performed by the owner |
| Fault class | Directory structure loss with allocation records intact — capacity reported as consumed while no entries present; content unwritten over |
| Equipment used | No format permitted and card removed from use · reported capacity compared against visible content before any conclusion · imaged write-blocked (DeepSpar USB Stabilizer 10Gb) · directory structures reconstructed from surviving copies · format-aware carving for camera containers alongside · footage validated by playback and reported by duration recovered |
The decode: two questions, two sets of records
How a device knows a card is full: it reads the allocation records — a map of which parts of the card are in use. That map says nothing about what the occupied regions contain or what any of it is called; it only reports occupied and free.
How a device knows what files are on it: it reads the directory entries — separate records giving each file a name, a size and a starting position. Those are different structures in different places, maintained together and damaged independently.
So what her two readings describe: allocation records reporting the card as occupied, and directory entries no longer readable. The card is genuinely full — of footage nothing can name. "Empty as if formatted" is what a card with intact content and lost directories looks like, and it is one of the more recoverable conditions in this archive.
The check that confirms it, and it takes seconds: look at the card's properties and compare used space against what is visible. If space is consumed and no files are shown, the footage is there. A genuinely formatted card reports itself as almost entirely free — so that one number distinguishes the good case from the bad one.
Why the card reported full during the shoot: quite possibly it was not. Damage to allocation records can make a card claim it has no space while capacity remains — which would mean the structures were already deteriorating during filming, and the "full" message was the first symptom rather than a normal end to the card. The failure did not happen overnight; it began while she was working.
Why that matters for her equipment: a card that reports full prematurely is a card to retire, not to reformat and reuse. Whatever caused it will do so again, and next time it may be discovered later.
What must not happen: no format, from any device. The computer will offer it, and a camera meeting the card will offer it too — which is why the card should not go back into either.
What is done differently for professional footage: validation by playback rather than file count, and reporting by duration recovered against the day filmed, because a client needs to know how much of the day exists rather than how many files came back.
On the bench
No format was permitted and the card removed from use, both the computer and the camera offering one. Reported capacity was compared against visible content before any conclusion — free space being calculated from allocation records while listings come from directory entries, so consumed capacity with no files shown confirms content present and directories lost. The card was imaged write-blocked behind the DeepSpar USB Stabilizer 10Gb, directories reconstructed from surviving copies with format-aware carving alongside, and footage validated by playback and reported by duration recovered.
The outcome
Capacity compared against content first, the card imaged and directories rebuilt with carving in parallel, reported by duration recovered. Free assessment, one fixed written figure including VAT; where a chip has to be removed, 50% of parts and labour is payable upfront with the balance only on success — otherwise no recovery, no fee. The decode: free space is read from allocation records and the file listing from directory entries — different structures, damaged independently. So a card that reports space consumed while showing nothing is full of footage nothing can name. Check the used space; that one number settles it.
Card that shows as empty without being formatted
Check the used space before anything else — it takes seconds and it settles the question. Free space is calculated from allocation records, which map which parts of the card are occupied, while the file listing comes from directory entries, which give each file a name and a position. They're separate structures and they fail independently. So a card reporting consumed capacity while showing no files is full of footage that nothing can currently name, which is a recoverable position; a genuinely formatted card would report itself as almost entirely free. Refuse every offer to format, from the computer and the camera both. And if it claimed to be full prematurely during the shoot, retire that card rather than reusing it.
Check the used space — then call Guildford Data Recovery on 01483 901310; imaged write-blocked, directories rebuilt from surviving copies with carving in parallel, footage reported by duration recovered.
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Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.