Using Partitioning to Reduce Slack

Since slack is dependent on the cluster size used for the partition, and the cluster size is directly linked to partition size, it is possible to dramatically improve the efficient utilization of the hard disk simply by dividing it into multiple partitions. The larger the current partitions are, and the more files on the disk, the greater the opportunity for improvement. (This applies only to systems using FAT16, since FAT32 supports disks up to 8 GB using 4 KB clusters).

Let's take the example of a 2 GB disk (usually called a 2.1 GB disk by hard disk manufacturers, since they talk in decimal gigabytes). Let's say that we have 24,000 files on our disk and each has an average amount of slack amounting to 60% of a cluster. Now consider various partitioning alternatives; we can either keep the disk in one piece or break it into smaller pieces. Here is the impact on (approximate) slack space:

As you can see, putting a 2 GB disk in a single partition is madness; typically 20% or more of the disk is going to be wasted, and you can cut that basically in half just by going to a pair of partitions. You can cut it much further by going to more partitions. In fact, the best solution might seem to be just going to 128 MB partitions, which drops slack down to a very small number. There's only one problem with this: you have to use 16 partitions! Do you really want your files spread over 16 disk volumes, from C: to R:? Most people don't. (I cringe at the very thought. )

The table shows that there is a tradeoff between saving slack and causing your disk to be broken into a large number of small pieces. Which option makes the most sense for you depends entirely on what you are doing with your disk, and on your personal preferences. I cannot stand having my disk chopped into zillions of pieces; I usually use 8 KB or 16 KB cluster-size partitions and sacrifice some more storage for the sake of what I consider "order". Others prefer the use of more, smaller partitions. You should also bear in mind the space tradeoff in using multiple partitions, something the "partitioning fanatics" (my pet name for people that like to chop a 1 GB disk into eight 128 MB partitions) often don't realize.

Note: You aren't required to make partitions that are exactly 256 MB, 512 MB, or whatever; they can be any size as long as they don't exceed the maximum for a given cluster size. So you could divide a 2 GB disk into five 400 MB partitions for example, but each of these would use the same cluster size that the 500 MB disk does in my example above.

Next: Partition Size Tradeoff: Slack Waste and "End of Volume" Space Waste