Could you please explain us what are these transport/hard errors...

when i ran the following command,

iostat -E | grep Errors

i got the following:

sd240 Soft Errors: 37 Hard Errors: 1144 Transport Errors: 0
sd578 Soft Errors: 0 Hard Errors: 890 Transport Errors: 0

Please tell me what does these mean and what has to be done.