A. If you need to create a file of a certain size and the file contents don't matter, you can use the Fsutil command as follows:

fsutil file createnew

For example,

fsutil file createnew d:\temp\1mbfile.txt 1000000

creates a 1MB file named 1mbfile.txt in the d:\temp folder. I've successfully used this command to create a very large file to reduce the amount of free space when I was using a buggy installation program that couldn't address too much free space.

Learn more from "How do I create a sparse file of a specific size in Windows XP and greater?"