Data Recovery Case File · Formatted & Logical Faults · Neither Side Is Authoritative
An Interrupted Copy Leaves You Unable to Tell Which Drive Is Complete
Her enquiry describes an ordinary interruption with an awkward aftermath. Copying files between drives when "the process stopped due to a file being in use, and so, not knowing where the copying had finished" she was left with two partly-overlapping drives and no way to tell which held what. The interruption itself is trivial — the danger is what people do next, which is to guess and start deleting.
| Media | Two hard drives following an interrupted transfer — copy halted by a file access conflict; completion point not recorded; overlap between source and destination undetermined |
| Reported situation | Files being copied between two drives · transfer halting because a file was reported as in use · point of interruption not known · extent of successful transfer not established · both drives retained |
| Fault class | Incomplete transfer with indeterminate overlap — no data loss unless the source is cleared on assumption; comparison required before any deletion |
| Equipment used | Both drives retained intact with no deletion permitted · file count and total size compared between source and destination · differences enumerated by path rather than by inspection · interrupting process identified before the transfer was resumed |
The decode: nothing is lost yet, and the way to keep it that way
What has actually happened: some files copied and some did not, and nobody knows where the boundary falls. Both drives are intact and everything still exists somewhere — this is an accounting problem rather than a loss.
Why it becomes a loss: when somebody decides the copy probably finished and clears the source to free space. That converts uncertainty into deletion, and this archive is full of the result. The single rule is that nothing is deleted from the source until the destination has been checked properly.
What checking properly means, and it is not looking: compare the file count and the total size of each folder on both drives. Those two numbers agreeing is meaningful; a folder appearing to be there is not — a folder can exist with half its contents, and the eye cannot tell.
Why total size is the better of the two figures: a partly-copied file has a name and an incomplete body. It appears in the count and falls short in the size, so counting alone would report a match that does not exist.
How to find the differences without doing it by hand: most systems can list a folder tree to a text file, and comparing two such listings identifies exactly what is missing. For thousands of files that is the only practical method, and it produces a list rather than an impression.
What the interruption itself was: a file that something else had open. Commonly an indexing service, a synchronisation client, a backup running in the background, or an application left open — and the fix is to close whatever holds it, or to copy that file separately afterwards.
Why the message is worth taking at face value: a file in use is a lock, not a fault. Nothing is wrong with either drive, and the transfer will complete once the conflict is resolved.
The habit that removes the problem entirely: use a copy tool that resumes and reports rather than the file browser. Anything that logs what it transferred and what it skipped turns this situation into a list instead of a guess.
On the bench
Both drives were retained intact with no deletion permitted — an interrupted transfer leaving everything extant while the boundary is unknown, so loss occurs only when a source is cleared on assumption. File count and total size were compared between source and destination, a partly-copied file appearing in the count while falling short in size, which makes size the more reliable measure. Differences were enumerated by path rather than by inspection, and the interrupting process identified before the transfer was resumed.
The outcome
Both drives retained, count and size compared by path, and the interrupting process identified before resuming. Free assessment, and no charge where the answer is a comparison you can run yourself. The decode: nothing is lost — everything is still on one drive or the other, and the only risk is deleting from the source on an assumption. Compare file counts and total sizes rather than looking, because a folder can be present with half its contents.
Copy that stopped partway between two drives
Don't delete anything from the source until you've compared them properly — nothing is lost yet, and clearing the source on an assumption is the only way this becomes a real problem. Compare file counts and total folder sizes rather than looking, because a folder can be present with half its contents and the eye can't tell. Total size is the more reliable figure, since a partly-copied file still appears in the count while falling short in bytes. For large trees, list both to text files and compare the listings, which gives you an actual list of what's missing. The interruption was just a file something else had open.
Delete nothing yet — call Oxford Data Recovery on 01865 593000; both drives retained, counts and sizes compared by path, differences enumerated rather than estimated.
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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.