ReFS allocation size

I was reformatting a drive for some Veeam backups and was trying to recall what I had set the ReFS allocation unit size to when I initially setup the drive. Well, I could not remember to save my life. Luckily, with a little command line action, it’s easy enough to find out what it was set it to.

The command line tool to use is fsutils. To see what options are available to us when using fsutils, we can run the following command.fsutils fsinfo /?

Using “E:/” as the drive we are checking out, we can run the following line to discover information about the volume itself. fsutil fsinfo volumeinfo E:

To view the specific ReFS info on this drive, we can run the following line. fsutil fsinfo refsinfo E: Take a look at value for the “Bytes Per Cluster”, this is where we can see that when this drive was formatted, it’s allocation unit size was set to 65k. 65k is also the recommended setting for Veeam destinations if you are using ReFS.