Data Recovery Case File · Cameras, Drones & Cards · The Boundary Is a Moment
A Date Boundary on Sequential Media Is Also a Position, So It Dates the Onset
Her enquiry describes a split with a timestamp on it. A card where "a partial amount of the files have become corrupted — some can read and others can't, after a certain date." That boundary is doing two jobs at once: cards fill in the order things are written, so a date boundary is also a physical boundary — and unlike a purely positional split, this one says when the degradation began.
| Media | Memory card with content readable up to a point in time and unreadable thereafter — boundary consistent in both date and write order |
| Reported situation | Memory card partially corrupted · files up to a certain date reading normally · files after that date not reading · boundary consistent across the content · recovery of the affected material sought · indicative cost queried |
| Fault class | Regional degradation with onset datable from content order — earlier written regions unaffected; failure beginning at an identifiable point in the card's use |
| Equipment used | Date boundary treated as locating the onset as well as the affected region · card read on fixed contact equipment independent of host enumeration · imaged with per-region read verification and unstable areas re-read across repeated passes · affected region mapped against the write-order boundary · content carved by signature within it and validated by opening |
The decode: why date equals position here, and what that adds
Why cards fill in order: allocation is sequential on media used this way. Each file is written after the last, so the order of writing and the order in which regions are occupied correspond closely.
What that makes her date boundary: a physical one. Files after a date occupy regions after a position, so the split she describes is a place on the card.
Why that would be useful on its own: it localises. Failure from a point onward means the card degrades from that point onward, rather than particular files being unlucky.
Now what the date adds that position alone would not: it says when. The last file that opens correctly was written before the fault existed, and the first that does not was written after or into it.
Why knowing when matters practically: it identifies what changed. A card that began failing at a datable moment invites the question of what happened around then — a device change, a fall, a period of heavy use.
Why that is worth pursuing even now: it may bear on other media. If a camera or a reader caused it, other cards used since are worth checking.
Why the earlier files opening is the reassuring half: the card reads. Content returning correctly establishes that the contacts, the controller and much of the memory are working.
What that narrows the fault to: a region rather than the device. A card failing everywhere would return nothing, and hers returns most things.
Why repeated reading is the method for the rest: results vary. A degraded region returns differently on different attempts, and comparing many passes reconstructs a correct result for a good proportion of it.
What must not happen meanwhile: no further use of the card. Writing anything new would be allocated into exactly the region that is failing.
On the bench
The date boundary was treated as locating the onset as well as the affected region — sequential allocation making write order and physical order correspond, so a date boundary is also a position, while the date additionally establishes when the fault began: the last file opening correctly predates it and the first failure was written after or into it. Earlier files reading correctly establishes working contacts, controller and much of the memory. Unstable areas were re-read across repeated passes.
The outcome
The boundary treated as locating both region and onset, unstable areas re-read across repeated passes, and content carved within the affected region. Free assessment, one fixed written figure including VAT; on cards where content has been deleted or overwritten, the figure is payable upfront. The decode: your date boundary is also a place on the card — and unlike a plain positional split, it tells us when the fault began, which invites the question of what changed around then.
When corruption starts at a particular date
Note the date precisely and stop using the card. On media that fills sequentially, a date boundary is also a physical boundary, so the split localises the fault to a region — and the date adds something a positional split can't: it says when the degradation began. That's worth thinking about, since whatever changed around then may have caused it, and any other cards used with the same camera or reader since are worth checking. Earlier files opening normally is the reassuring part.
Note the date — call Cambridge Data Recovery on 01223 655015; the boundary treated as locating both region and onset, read on fixed contact equipment, unstable areas re-read across repeated passes.
Request a quote online →
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.