Data Recovery Case File · Desktop Externals & Aging Drives · It Answered Incorrectly
A Wrong Capacity Is a Drive Reading Its Own Configuration and Getting It Wrong
His enquiry supplies figures rather than adjectives, which makes it immediately diagnosable. A drive reporting geometry of roughly five hundred cylinders where the model should report over two hundred thousand — a mis-statement of its own size by a factor of hundreds. The drive is answering the question and answering it wrongly, which places the fault in a small reserved region rather than anywhere near his content.
| Media | 2TB hard drive reporting geometry inconsistent with its model — cylinder count reported as a small fraction of the correct figure; device otherwise enumerating |
| Reported situation | Hard drive presenting to the host · reported geometry inconsistent with the drive model · cylinder figure reported as a small fraction of the expected value · drive identified by model, serial and firmware revision by the owner · content required |
| Fault class | Service area corruption affecting capacity descriptors — drive enumerating and reporting incorrect configuration; user regions unaffected by the location of the fault |
| Equipment used | Mis-reported geometry interpreted as service area corruption rather than physical capacity loss · device addressed through hardware with imposed timeouts rather than the host stack · service area modules read and reconstructed in vendor technological modes · correct geometry restored to a working copy before imaging · imaged write-blocked at the block level under capped timeouts |
The decode: where a drive gets its own size from, and what a wrong answer means
Why a drive has to be asked its size at all: the host does not know it. Capacity, geometry and addressing limits are all reported by the drive when it introduces itself, and the machine believes what it is told.
Where the drive gets those figures: a reserved area on the platters holding its own configuration. The drive reads that region during start-up and reports from it, so its self-description is stored data like anything else.
Why that means it can be wrong: stored data can be corrupted. A configuration region damaged in the right place produces a drive that answers confidently with an incorrect number.
Why a wrong answer is more informative than no answer: the drive read the region and returned something. Power, rotation, positioning and the reserved area are all functioning at least partially, which excludes a great deal.
What the specific error indicates: the reported figure is a small fraction of the correct one. A truncated or partially-read descriptor produces exactly that, rather than a random value.
Why that matters for what the host then does: a machine told the drive is small addresses only that portion. Content beyond the reported capacity is unreachable through any ordinary connection — invisible rather than absent.
Why his content is very likely intact: the fault is in the drive's description of itself, which occupies a reserved region. User data sits elsewhere and is untouched by a corrupt configuration.
Why no host-side tool can address it: everything an operating system does is bounded by the capacity the drive declares. Recovery software asked to scan a drive will scan the small portion it was told about, which is why such tools return almost nothing here.
What is done instead: the drive is addressed through equipment that communicates in its own diagnostic modes, where the configuration region is read and reconstructed directly. Correct geometry is restored to the working state and the full capacity becomes addressable.
Why quoting the model, serial and firmware revision was worth doing: the correct figures for that family are known. Establishing what the drive should report is a prerequisite to correcting what it does report, and he has supplied it.
On the bench
Mis-reported geometry was interpreted as service area corruption rather than physical capacity loss — capacity and geometry being reported by the drive from a reserved configuration region on the platters, read at start-up, so a corrupted descriptor produces a confident incorrect answer. A host told the drive is small addresses only that portion, rendering content beyond it unreachable rather than absent, and bounding every host-side tool. Service area modules were read and reconstructed in vendor technological modes.
The outcome
Mis-reported geometry read as service area corruption, the device addressed through hardware, and correct geometry restored to a working copy before imaging. Free assessment, one fixed written figure including VAT; where a drive has to be opened, 50% of parts and labour is payable upfront with the balance only on success — otherwise no recovery, no fee. The decode: your drive is answering and answering wrongly, which is more informative than silence. Its own size is stored data, and a corrupt descriptor makes everything beyond the reported capacity invisible rather than absent.
A drive that reports the wrong capacity
Don't run recovery software against it, because everything an operating system does is bounded by the capacity the drive declares — a tool told the drive is small will scan only that small portion and return almost nothing, which is not a finding about your content. A drive reports its own size from a reserved configuration region on the platters, so a wrong answer means that region is corrupt rather than that capacity has been lost. Your content sits elsewhere and is invisible rather than absent. Quote the model, serial and firmware revision, as you have.
Don't scan it — call Manchester Data Recovery on 0161 871 0788; mis-reported geometry read as service area corruption, addressed through hardware, correct geometry restored before imaging.
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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.