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RDR / Casebook / Every Copy Stopped on a Redundancy Check

Missing or corrupt files · job record · RDG-2025-1461

Every Big Copy Halted on the Same Words.

It had lived in a dock on an office shelf for years. Then the power went, and from that point nothing would copy cleanly. Single files at first, whole folders after that, and always the same stop: cyclic redundancy check. Swapping the lead changed nothing at all. Neither did carrying it down to the works and plugging it into the laptop. Neither did two goes at repair — Windows was checking it two nights running and neither morning had it got to the end. Thirty years of shop drawings sat on that disk, the work of a metal fabricator on the Robert Cort estate in Reading: every stair and every handrail I have made since I set up.

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What actually caused it.

That message carries far less meaning than people put into it. One fact is all it reports: what came back off the drive did not agree with the checksum filed against it. Nothing more. Two unrelated faults produce the same wording — bookkeeping that has drifted on hardware in perfect health, or a surface that will no longer hold what was written to it. Guess it is the first when it is the second and you make things worse, which is where guessing gets expensive. Against a weak patch, Windows simply keeps asking, over and over, until the sector answers or the drive stops replying. Two nights had already gone that way.

What this one needed on the bench.

How every job runs →
Bench toolsIts part in this jobWhy it is here
DeepSpar Disk Imager 4Imaged under a retry ceiling, logging the poor ground and moving past itIt maps the heads before anything is taken off, keeps to one platter side per pass, and stays in charge of the resets, the timeouts and the power
R-Studio TechnicianRebuilt the volume from the image rather than from the driveHandles almost any file system, and puts an array back together off the images
ACE Lab PC-3000 ExpressQuestioned the firmware before a sector was touched: attribute trends, the grown defect list, and two overnight sessions logged in itGets into the manufacturer's own service mode, which plain ATA never reaches

What the bench did.

01

The drive keeps records, so question it first

The firmware was interrogated before anything was imaged, and it answered plainly. Reallocated sectors stood high and were still climbing, with more queued behind them awaiting their turn. In the power-on log, two long sessions lined up almost hour for hour with the two nights he had spent scanning. That put the fault in the surface and not in the bookkeeping.

02

Cap the retries, because retries are time

The limits were agreed before imaging: short timeouts, a fixed number of tries, and any band that pushed back got logged, skipped and left alone. Those skipped bands were given one short run right at the end. That is arithmetic rather than stubbornness. An hour spent on one bad sector can cost you the thousand good ones queued behind it.

03

Power the disk off, and work on the image

The Toshiba was switched off as soon as the copy was safely written, and stayed off. What came out was better than the counters had led us to expect. No part of the folder tree was absent, and the losses gathered in a single band beneath one run of scanned sheets. Each of the absent ones appears in the report under its own filename, so what he has is a list for the plan chest rather than an apology.

What went back.

One folder had been named to us on the telephone as the one that mattered first: staircases and balustrades on buildings the public walks through daily. It was opened and read before the invoice was raised. The archive went back on a new disk, whole except for the sheets listed in the report. Two of them exist as paper prints at the works, and those can be drawn again. The rest belong to jobs finished before he took the firm on, and that paper went years ago.

The short version: Honesty is all a CRC error amounts to: the drive telling you the block did not verify. Take the one clean copy it can still give and stop asking it for another. Post it in and we will tell you which of the two faults you have — that answer costs nothing, a single drive is £300 + VAT, and the figure is fixed in writing before any work starts.

If that sounds like yours, stop there.

Post it in as it is, switched off. Looking costs nothing, and you get one fixed figure in writing before any chargeable work begins — £250 + VAT for a card or stick, £300 + VAT for a single drive, from £500 + VAT for RAID and NAS. On most jobs, nothing is charged unless your data comes back.

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