Data Recovery Case File · Formatted & Logical Faults · The Rescue That Was Costing Him

Slow Drive With Disk Errors: Stop Copying Files Off

His enquiry described someone doing the right thing in the wrong way, which is the most frustrating situation in this trade and one of the most common. A hard drive of a few years old: "recently it's started having awful reading speeds and throwing disk errors. Some of the files — PNGs, MP3s, MP4s — are showing up as unsupported file types and some pictures are completely black. A lot of the data is still readable, it's just very slow to pull off onto a different drive due to Windows not being able to copy corrupted files easily." Then the sentence that shows he understands the stakes: "I really just need the files taken off to make sure no more damage is done." That instinct is exactly correct. Unfortunately the method he is using to act on it is itself the thing causing further damage — and this page explains why, because the reasoning is not obvious.

The decode: why manual copying is the worst evacuation method

What the symptoms mean: the pattern across mixed file types is consistent and informative. Files reported as "unsupported types" are files whose opening bytes — the header identifying what they are — could not be read correctly, so the system cannot recognise them. Pictures that render completely black are images whose data failed right at the start of decoding. Both describe the same underlying fact: parts of the drive no longer return reliable data, and any file unlucky enough to have a critical portion in one of those regions comes back damaged. That is degrading media, and the slowness is its signature — the drive retrying failing reads internally, seconds at a time, where microseconds belong.

Why his method is hurting: three compounding reasons. First, Windows has no timeout control. Faced with a sector that will not read, it waits, and waits, and retries — which is why the copy is slow. Every one of those retries is the head passing over a weak region again, and repeated passes over failing areas accelerate their deterioration. Second, it works in catalogue order: it copies whatever comes next alphabetically, so the drive's dwindling number of good reads is spent according to filename rather than importance or difficulty. Third, and worst, Windows tends to abort a whole copy operation when it meets an unreadable file, so people restart the copy — which re-reads everything already copied, doubling and tripling the load on a drive that is failing.

The cruel arithmetic: he is spending the drive's remaining life to rescue files in an inefficient order, using a tool that hammers exactly the regions that are dying. The longer it runs, the fewer sectors remain readable, and files that would have come back cleanly last week may not this week. His stated goal — stop further damage — is achieved by the opposite of what he is doing: stop the copying.

What the right method does differently: one imaging pass with per-sector timeouts, so a failing sector is given a strict budget and then skipped rather than retried indefinitely, keeping the pass moving. Healthy regions are captured first and completely, so the bulk of his data is secured while the drive is at its strongest. Weak regions are revisited afterwards on their own passes, where repeated patient reads often recover data that a single attempt would not. And everything afterwards happens on the image, where a file can be examined a hundred times at no cost — including the partially damaged ones, which can frequently be repaired or partially reconstructed once there is a stable copy to work from.

On the bench

The copying stopped at the door, which was the single most valuable step in the case. The Atola Insight Forensic assessed the media and heads to establish how much margin remained and where the failing regions lay, and imaging ran on the PC-3000 Express under Data Extractor with per-sector timeouts enforced and the sweep prioritised — healthy expanse first and completely, weak neighbourhoods deferred to later passes where repeated reads recovered sectors that had defeated Windows entirely. On the completed image, the truncated and blank files were reconstructed where the newly recovered sectors allowed, and every file was validated by opening — images rendered, audio and video played — before delivery on fresh media.

The outcome

The evacuation completed properly in one managed pass, with damaged files repaired from sectors recovered on later reads, all validated and delivered. 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, for anyone patiently copying files off a failing drive: your instinct is right and your method is the problem — Windows has no timeout control, so it retries failing sectors endlessly and hammers precisely the regions that are dying; it copies in catalogue order, spending the drive's remaining reads by filename rather than importance; and it aborts on unreadable files, so people restart and re-read everything again. Files showing as unsupported types or rendering black are files whose critical portions fell in failing regions — recoverable, often, but not by trying again harder.

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.