Identify which application is reading/writing on the hard drive

Question

Is there a similar tool to Windows 7 Resource Monitor in OS X that can show me how many I/O operations are being performed for each active process?

Answer 1

You can open a wide Terminal window and enter the command:

sudo fs_usage -f filesys

This will show all filesystem activity on the system, as it occurs. It will show not only which processes are accessing the filesystem, but also what they are doing.