Why hard drive read speed lower than USB drive's?

Question

Just try testing my hard drive and USB drive, but I wonder that hard drive read speed is much slower than USB drive. Why?

Answer 1

This is almost certainly due to the fact that you're performing a random read, as opposed to a sequential read. This means you are reading data from random locations on the hard drive platter. On a mechanical hard drive, particularly ones with large data capacity, the 'seek time' (which is how long, on average, it takes for the HDD to locate a data block and move the read head to it) is large. If the drive is having to seek for every block it reads, this will cause very slow reads and writes. Conversely, solid state storage does not have to physically move a read head to the data location, so all that has to be done is a lookup to work out where the data is. As a result, random read and writes tend to be faster on small mechanical drives or solid state storage.

Try adjusting the command to: winsat disk -read -seq -drive c: