Como criar arquivos para teste no Windows

Cria um arquivo de 1GB no Desktop

fsutil file createnew c:\users\steve\desktop\1gb.test 1073741824

Cria uma arquivo de 2GB no pen drive:

fsutil file createnew E:\2gb.test 2073741824

The key is to input the size of the file in bytes so here are some common file sizes to save you from math:

1 MB = 1048576 bytes

100 MB = 104857600 bytes

1 GB = 1073741824 bytes

10 GB = 10737418240 bytes

100 GB =107374182400 bytes

1 TB = 1099511627776 bytes

10 TB =10995116277760 bytes

Referência:

Quickly Generate Large Test Files in Windows (tweaks.com)