14.5. Optimizing Storage Capacity

Although quotas can help you manage storage capacity on NTFS volumes, there are other issues to consider, including some that apply to FAT16 and FAT32 file systems. This section covers two topics that will help you optimize storage capacity: cluster size and compression.

14.5.1. Optimizing cluster size

As explained earlier in this chapter, a sector is the smallest unit of physical storage space on a disk. The smallest allocation unit, however, is the cluster. When Windows Server 2008 parcels out storage space, it does so by cluster. The significance of this is that cluster size has a direct impact on how efficiently the file system stores data. For example, assume a volume uses a cluster size of 64K. You store several files, each 32K in size. Although two files could possibly fit in one cluster, that's not how Windows Server 2008 allocates the space. Instead, each file resides completely in its own cluster. That means that each file takes up just half of its allocated space, with the rest being unused. This is often called sector slack. Take it to the extreme in this example and assume that all your files are like this, and you'll waste half of the space on the volume. A 32GB volume would hold only 16GB of data.