Changing the NTFS Allocation for win2012R2 VM with or without reformatting

Hi community 

Benjamin Niaulin has written an excellent article on maximising the performance of SharePoint 2013 on a VM. Now one of the major improvements it increase the NTFS Allocation size as this will make SQLServer have few reads .. Ok but since my vm is set at the default 4K, how can I quickly accomplish this without reformatting or do I have to perform a windows backup, reformat or recreate the VM with the new allocation size.

Daniel

Freelance consultant