Just a quick example of how to use dd to test drive read/write speed. NOTE: Dont do this a lot or you could shorten the live of your drive since youre making arbitrary writes.
Reading
sudo dd if=/dev/zero of=/tmp/test.img bs=1G count=1 oflag=dsync
This command will write 1G of zeros to an arbitrary file of your choosing. Feel free to delete it when you’re done.
Your output will look a little like this.