Testing USB Drive Capacity
USB storage devices can lie.
The controller chip reports capacity to your computer, but it only knows what the manufacturer programmed it to say. There’s no verification that the actual memory chips match.
The Scam
Vendors buy cheap 512MB or 1GB drives, reprogram the controller to claim 16GB or 32GB, and resell at premium prices. Your operating system believes the lie.
The danger: data written beyond the actual capacity simply disappears. No error message when writing. You only discover the problem when trying to read files that no longer exist.
This isn’t just a dark-web problem. Counterfeit drives have appeared in legitimate retail stores.
The Solution
Use H2testw (Windows GUI) or H2Test (command-line) from heise.de. These utilities:
- Write large files across the entire claimed capacity
- Read the files back and verify data integrity
- Report the actual usable storage space
A genuine 16GB drive passes. A fake 1GB drive claiming 16GB fails spectacularly.
The Rule
Test new storage devices immediately after purchase. Before you trust them with important data. Before you’re stuck at a conference with a corrupted presentation.
The few minutes of testing are worth it. The alternative is discovering the fraud when it’s too late.