isn’t pretty, but it’s brutally honest. If you buy flash storage online, keep this 600KB tool on your desktop. Run it before you trust any drive with your data.
Flash memory inherently contains some defective sectors, but excessive bad blocks indicate poor manufacturing quality. MyDiskTest scans the drive's NAND flash memory to identify bad blocks and can even perform "soft shielding" to mark these sectors as unusable, preventing data from being written to unreliable locations. Mydisktest V2.42