In this article, I'll introduce you to the UDF file system. Before you can appreciate the way UDF works, you must understand how clusters work. A cluster is the smallest possible unit of hard disk storage. Clusters range in size depending on the size of the hard disk and the file system used. However, regardless of the size of the cluster, even a one-byte file consumes an entire cluster.
Larger files span multiple clusters.
The first 32KB is stored in the first two clusters, which are completely used. However, the remaining 2KB will be placed in the last cluster. So, 2KB of the last cluster is used and 14KB is wasted. As you can imagine, having a large cluster size can result in a lot of wasted hard disk space. Therefore, the trick to getting back some of your hard disk space is to reduce the cluster size.