Eric Cobb has a tiny script for us:
There seems to be some ongoing debate around whether or not formatting your data and log drives with 64KB allocation unit size even matters anymore. I would encourage you to do your own research to determine if you want to do this or not. My personal take on it is: if it doesn’t hurt, and it may help, and it only takes 2 seconds to click the “go” button on my PowerShell script, then I would rather go ahead and do it and not need it than not do it and wish I had later down the road.
I don’t have a strong opinion in that debate, myself, so I’ll just say that if you want to see how to do this in a couple lines of Powershell code, check out Eric’s post.