Raw Seagate external hard disk data recovery

Raw files system is a kind of system error. We need to fix the Seagate external hard disk if it turns to raw. The problem is that we can not open the raw external hard disk, not to mention view files saved on it at the previous time or store new data on it. The way to solve the Seagate external hard disk raw problem is to format it. And then we can convert it to normal system which we want. But if there are files useful and crucial still saved on that problematic external hard disk, we should start data recovery at first.