Disk Read/Write Bytes using API code

Sure. You will need to use low-level disk access, the following raw Windows API:
http://msdn.microsoft.com/en-us/library/windows/desktop/aa364939%28v=vs.85%29.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/aa363858%28v=vs.85%29.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365541%28v=vs.85%29.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365467%28v=vs.85%29.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365468%28v=vs.85%29.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365747%28v=vs.85%29.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/aa365748%28v=vs.85%29.aspx[^].

The P/Invoke equivalents are already written for you:
http://www.pinvoke.net/default.aspx/kernel32.createfile[^],
http://www.pinvoke.net/default.aspx/kernel32.setfilepointer[^],
http://www.pinvoke.net/default.aspx/kernel32.readfile[^],
http://www.pinvoke.net/default.aspx/kernel32/ReadFileEx.html[^],
http://www.pinvoke.net/default.aspx/kernel32.writefile[^],
http://www.pinvoke.net/default.aspx/kernel32/WriteFileEx.html[^].

For the file names representing the whole disk, you can use the drive names as they are registered in the system, which you can obtain from WMI (the names started with '\\').

If you want to work not with physical drives but with partitions, you will have do delve into all those partitioning systems and parsing of the partition tables, boot records, all that stuff. This is quite a big topic itself. You can start here:
http://en.wikipedia.org/wiki/Disk_partitioning[^],
http://en.wikipedia.org/wiki/Partition_table[^],
http://en.wikipedia.org/wiki/Master_Boot_Record[^],
http://en.wikipedia.org/wiki/GUID_Partition_Table[^],
http://en.wikipedia.org/wiki/Boot_Engineering_Extension_Record#BEER[^].

Now, most or all of the operations you need may require elevated privilege for your application. This is how you do it manually:
http://4sysops.com/archives/vista%E2%80%99s-uac-8-ways-how-to-elevate-an-application-to-run-it-with-administrator-rights[^],
http://www.sevenforums.com/tutorials/11841-run-administrator.html[^].

In practice, instead, you will need to add an application manifest and embed it in your assembly to request elevation from the very beginning. This is explained here:
http://msdn.microsoft.com/en-us/library/bb756929.aspx[^].

—SA

creizlein wrote:

Hello Sergey, First off, thank you very much for your reply, it did give me some good information, but maybe i expressed bad myself, I am not looking into ways of writing and reading files to the disks but instead to get the amounts of bytes that are being read/written to them, pretty much like a disk monitor usage.

Sorry for not answering to this request, but it really was pretty unclear, in first place.

For such things, you need the class System.IO.FileSystemWatcher:
http://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher%28v=vs.110%29.aspx[^].

You need to be aware of certain problems though. Please see these CodeProject articles:
FileSystemWatcher - Pure Chaos (Part 1 of 2)[^],
FileSystemWatcher - Pure Chaos (Part 2 of 2)[^].

—SA