Quickly create large file on a Windows system

You can use the Sysinternals Contig tool. It has a -n switch which creates a new file of a given size. Unlike fsutil, it doesn't require administrative privileges.

fsutil file createnew <filename> <length>

where <length> is in bytes.

For example, to create a 1MB (Windows MB or MiB) file named 'test', this code can be used.

fsutil file createnew test 1048576

fsutil requires administrative privileges though.