Performance - Hard Disk Drives

Hard Disk Cluster Sizes

Coming from a FAT background, where a text file with one sentence can take upwards of 32KB on a large disk volume, small 2KB clusters sound real fine. You can potentially save multi-megabytes of hard disk space by using smaller clusters, especially if you use a program that generates many small files (like Internet Explorer).

On the other hand, one large file will use many of the small 2KB clusters, and you'll probably find file fragmentation to be more problematic than it was with the larger (8K-32K) clusters, especially if you edit the file often. So in exchange for saved disk space, you give up some apparent performance unless you keep your disk optimized (defragmented).

With a FAT-formatted drive, the only way to determine cluster size is by partitioning your drives to certain sizes. With NTFS, however, you can opt to format any size partition with either 512, 1024, 2048, or 4096 -byte clusters during format using the following structure:

FORMAT <drive> /FS: <file system> /A: <cluster size>

example:
FORMAT c: /FS: ntfs /A: 2048

cf the Knowledge Base article /A switch.

This Knowledge Base article tells you the default cluster sizes for both FAT and NTFS volumes of various sizes. You can use Windows NT Diagnostics (the "Drives" tab) to check your cluster size: just select the Properties of the Drive in question.

File Fragmentation

Now that we've got disk structure covered, it's prudent to say that file fragmentation is a fact of life you're going to have to deal with no matter what file system and cluster size you use. Furthermore, file fragmentation determines to a great extent how fast your system seems to perform, and short of frequent drive re-formatting (!!!), a disk optimizer is almost necessary.

There are three mainstream disk optimizers available: Norton SpeedDisk (part of Norton Utilities for NT, and also available as a standalone trial version); Diskeeper (both in a full version and a free Lite version); and PerfectDisk NT.

What they won't do is defragment certain "hands-off" files, like the Master Boot Record (NTFS) or your paging file. However, for your paging file, you can let the optimizer pack files together to create a large, contiguous free space, then set your paging file to nothing, reboot, and create a new paging file. Be sure to set the minimum and maximum page file sizes equal so the page file can't grow (thus fragmenting itself again).