Cause of loss · RAW and corruption
Show Windows a volume it cannot read and it offers Format, because Format is the only tool it carries for the job. The disk is plainly there — as it is on the RAW volumes that reach us from across Cardiff. The structures written on it no longer add up. Most of the data lost to corruption goes in the couple of minutes after that box appears, rather than to the corruption behind it.
Describe the symptoms to an engineer
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| Warning signs | What has gone wrong | Do this now |
|---|---|---|
| The disk in drive X: is not formatted. Do you want to format it now? | Windows cannot read the file system, so it labels the volume RAW | Do not hit Format |
| CHKDSK is not available for RAW drives. Type: RAW. | CHKDSK refusing the job: there is nothing there it can fix | Take it off the machine |
| File or directory corrupted and unreadable (0x80070570) | MFT records Windows can no longer parse | Shut the window; stop browsing |
| Disk structure is corrupted and unreadable (0x80070571) | Harm to the partition table or to the MFT | Image first, repair afterwards |
| The parameter is incorrect. Drive X:\ is not accessible. | Broken structures sitting on top of bad sectors | Assume the drive is failing |
| The disk does not contain a recognized file system | No file-system metadata left at all | The contents are still there |
| On a Mac: the disk is not readable by this computer | The same fault in Mac wording; Initialize is the button to avoid | Choose Eject, not Initialize |
The diagnosis costs you nothing. Every item that arrives is logged under a case number of its own, and an engineer works out what has actually failed — then tells you plainly which files can come back and which cannot. The price follows that: one fixed figure, in writing, and no work begins until you have read it and said go ahead.
Nothing is repaired until a sector-by-sector copy of the disk exists, with every region that reads poorly noted and left until the end. Broken structures and failing hardware tend to arrive together, so a single image covers both.
The boot sector, the partition table and the MFT are rebuilt inside the image and never on your disk, which means a step that goes wrong can be undone.
However badly the MFT has fared, the contents sit in the same clusters as before. Each file is recovered from the image by its signature alone, and as much of the folder structure comes back as the surviving evidence allows.
Nothing is billed while you are still deciding. A complete listing of what came off the drive reaches you first, and the invoice only follows your yes. Files travel back on media bought new for the job, return postage ours, and we do not close it here until every one of them opens on the machine you will use.
Every repair tool shares one habit: CHKDSK, First Aid inside Disk Utility, whatever free RAW fixer a forum recommends — each of them writes to the same disk it is supposed to be saving. If the hardware below is healthy, that costs you nothing. If it is not, a job that would have come back whole comes back in fragments. The cost of caution is a day's wait for an image.
A write was still going when the cable came out of the socket. Next morning Windows offered one thing: a prompt to format the disk. So the whole 4TB was imaged first, and only then were the boot sector and the broken MFT mirror mended — on the copy, never on the original. Fifteen years of client jobs went home with the folder tree intact.
Turn it down. A format lays down a new and empty file system where the damaged one was, right on the records that still carry your folder names and dates. Those records are what a rebuild is made from.
Because the structures that describe the volume no longer make sense to it. The damage usually sits in the partition table, the boot sector or the MFT. Your actual files are underneath all that, untouched.
On a RAW volume it refuses to run at all, so there is nothing to gain from it. Against that, a drive already on its way out gives up a little more with every pass. Repairs belong on an image, not on the disk itself.
Quite likely, and you are far from the first. Interrupt a write by pulling the cable and the index is left half-updated, pointing at files that are themselves complete.
A failing drive has only so many starts left in it. Spend none of them. Keep the power off, and the free diagnosis will tell you what is still readable.