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File System Performance Factors

There are several factors related to how the disk is logically structured and the file system set up and maintained, that can have a tangible effect on performance. These are basically independent of the hard disk and will have similar impacts on any hard disk. See the section on the file system for much more information on these issues:

• File Structure and Cluster Size: When using DOS or a Windows variant that uses DOS-based file structures, the choice of cluster size has an impact on real-world performance. In a nutshell, larger clusters waste more space due to slack but generally provide for slightly better performance because there will be less fragmentation and more of the file will be in consecutive blocks. There is also less overhead to be maintained because the file allocation table is smaller. Similarly, a file system using FAT32 will have different performance characteristics than one using FAT16.
• Fragmentation: A fragmented file system leads to performance degradation. Instead of a file being in one contiguous chunk on the disk, it is broken into many pieces, which can be located anywhere on the disk. This means forcing additional seeks when reading a large file, and seeks are very time-consuming. Defragmenting a very fragmented hard disk will often result in small improvements in benchmark scores.
• Partitioning: The way that a disk is partitioned can affect its performance. This is related to the cluster size issue, because smaller partitions generally mean larger clusters and vice versa. This also is affected by zoned bit recording. If you partition a drive into three logicals, the first one will have the best performance because it is using cylinders at the outer edge of the disk.

Next: Redundant Arrays of Inexpensive Disk (RAID)

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