Explainer
Undelete vs Deep Scan: Which Data Recovery Method Do You Need?
Data recovery tools use two fundamentally different methods. Knowing which one fits your situation saves time and sets the right expectations for what you’ll get back. Here’s the plain-English version.
Method 1 — Quick scan (undelete)
Every drive keeps a catalogue of what’s on it: NTFS uses the Master File Table; FAT and exFAT use directory entries. When you delete a file, the catalogue entry is marked as free, but it — and the data it points to — usually stays put for a while.
A quick scan reads that catalogue and finds the deleted-but-intact entries. Because the record is still there, you get the file back with its original name, folder path and dates. It’s fast and high quality.
Use it when: you deleted files (Shift+Delete, emptied Recycle Bin, cleared a card) and the drive itself is otherwise healthy.
Method 2 — Deep scan (signature carving)
Sometimes the catalogue is gone — after a format, corruption, or a wiped partition. There’s nothing left to read the filenames from. A deep scan ignores the filesystem and reads the raw disk surface, recognising files by their internal signatures (the distinctive bytes that mark the start and structure of a JPEG, PDF, ZIP-based Office file, SQLite database or MP4).
It recovers the file’s contents, but not its original name or folder — that information lived in the catalogue that’s now gone. Honest tools label these clearly and give them sensible names.
Use it when: the drive was formatted or corrupted, or a quick scan found nothing.
Side by side
| Quick scan (undelete) | Deep scan (carving) | |
|---|---|---|
| Reads | Filesystem records (MFT / directories) | Raw disk, by file signature |
| Speed | Seconds | Minutes to hours |
| Original filename & folder | ✓ Yes | ✕ No (honest names given) |
| Any file type | ✓ Yes | Known signatures only |
| Works after a format | ✕ No | ✓ Yes |
So which should you run?
Start with a quick scan — it’s instant and gives the cleanest result. If it doesn’t find your file, or the drive was formatted or is throwing errors, switch to a deep scan. DéjàFile offers both from one window, and grades every result HIGH/MEDIUM/LOW either way so you know what will genuinely come back.