"find -name io_file* will search in the current directory and below only. If you want to search the entire harddrive, you need to specify the path: find / -name io_file*. Same thing goes with grep -r; it will only search in the current directory and below.
The find utility is very handy, but it may be a little counterintuitive to use. My recommendation is that you read the find man-page (man find), it is well worth the invested time."
"Because you didn't give grep a file, it is operating on standard input and waiting for you to type something. It's the wrong command anyway. As for find you need a directory to start from and have to put io_file* in quotation marks, otherwise it gets expanded by the shell:
find / -name ""io_file*""
You can also use locate ""io_file*"" which is faster but may be inaccurate."