First published on TECHNET on Jan 13, 2017 Microsoft’s file systems organize storage devices based on cluster size. Also known as the allocation unit size, cluster size represents the smallest amount of disk space that can be allocated to hold a file. Because ReFS and NTFS don’t reference files at a byte granularity, the cluster size is the smallest unit of size that each file system can reference when accessing storage. Both ReFS and NTFS support multiple cluster sizes, as different sized clusters can offer different performance benefits, depending on the deployment. In the past couple weeks, we’ve seen some confusion regarding the recommended cluster sizes for ReFS and NTFS, so this blog will hopefully disambiguate previous recommendations while helping to provide the reasoning behind why some cluster sizes are recommended for certain scenarios. IO amplification Before jumping into cluster size recommendations, it’ll be important to understand what IO amplification is and why m...