|RAW isn't a real file system, just what Windows calls it when for any reason it is unable to determine what the actual file system is. This is usually due to corruption, often caused by a physical fault in the drive itself. The simple solution is to format the drive, which will of course result in the loss of all data it contains. If this is a problem then the drive is not being used as intended. If the format fails then the drive should probably be replaced.|
Flash drives are the least reliable of all modern storage media and should not be trusted for primary storage of important files. They should be used as a transport media where there is always a copy of files on some other media, such as a hard drive.
Having a single copy of important files on a flash drive, or any media for that matter, is asking for trouble.