If you've been working with Windows NT and Windows 2000 for a while, you're probably familiar with the FAT 16, FAT 32, CDFS, HPFS, and NTFS file systems. 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.