A USB 2.0 Disk is a type of external hard drive that uses the USB 2.0 interface to connect to a computer. USB 2.0 Disks are designed to provide high-capacity storage for computers, and are often used for backing up data or storing large files.
NAND flash needs free space for wear leveling and garbage collection. Keeping 10-20% of the drive empty reduces the chance of controller errors and "false full" reports.
: Even if the drive says "Full" or shows "0 MB" capacity in Disk Management, it’s usually not a space issue. It means the controller chip is powered on, but it can't "see" any storage memory to report a real size. Common Symptoms