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Got a New Computer? Partition it! (part 1 of 2)

Copyright ©, Myles White, 2000

If you buy a new PC this month, particularly if it falls into the mid- to high-end category, the chances are very good that it will come with a high-capacity hard disk drive. The most common type of drive – often referred to in the ads as an IDE, EIDE, UDMA, or ATA drive (in today's market the terms are interchangeable) – comes with a variety of storage capacities ranging from under 8.4 gigabytes (GB) to upwards of 81 GB, although typically in that mid- to high-end category, they're more likely to be in the 27 to 40-odd GB to as high as 60 GB range.

Having a large capacity hard drive is a good idea (because data always expands to fill the container and today's software products produce hugely bloated files). Prices don't start accelerating until you get into the higher end but, this article isn't about their cost.

It's about how much of that storage space you may be wasting.

Space wasted

One of the things I've noticed over the past 18 months or so is that many of the name brand systems sent to me for review, complete with large hard drives, come with the drives set to use all of the space in one large partition. In other words, the whole drive is drive C:\. It isn't sliced up into smaller bits, giving you, for example, drives C:\, D:\, E:\ and so on. Today, we're going to discuss why you should care, but I'm going to have to dip into a little technical stuff to fully explain it. 

Hard disk drives may have one or several platters in them (think of something resembling a stack of very thin pancakes). Each platter is covered with a very thin layer of magnetically responsive molecules that can be changed when the drive's write head produces a variable electrical current. The changes in the patterns created in the molecular recording medium can also be read by the drive's sensitive read head.

However, before you can use a disk, it has to be formatted so that whatever operating system your computer uses can find information stored on the disk (if it was stored completely randomly, it would not only take forever to find anything - assuming you could - but nothing would stop the system from writing data over top of something you wanted to keep). In order to keep the bits of data organized, your disk is ordered during the formatting process so that it contains tracks, sectors, and clusters.

Each track on a hard disk is divided into sectors and each sector is numbered. Within each sector, there are going to also be numbered clusters (defined as the smallest area in which data can be contained). If you want to think of it another way, imagine that the tracks are streets, the sectors are apartment buildings, and the clusters are individual apartments.

The number of tracks and sectors are determined by the capacity of the disk (the size of the city, the number of streets it can have, and the number of buildings you can put on each street). The number of clusters is determined by the system the computer uses to keep track of where they are, also called the file allocation table (or FAT). In our analogy we're going to pretend that the post office in our mythical city has a finite number of pigeon holes in its office in which to sort the mail for our apartment dwellers and that places a limit on the number of apartments allowed.

Depending on the age of your computer and whether it runs Windows 95 or earlier, or Windows 95 OSR2 or later, that file allocation table may use 16 or 32 bits of data to describe the location of any specific cluster. The total capacity of any partition on the disk (the physical size of the city), plus the file scheme used (in this case, FAT16 or FAT32), will determine the cluster size. (In our analogy, the post office may have a small or large building in which to do its sorting).

Before we go on, there's one other thing you need to understand about clusters and sectors. Sectors are divisible and can have a part of one or several files in them. Clusters are not divisible. If you fill part of a cluster, all of it is considered used. It's just like our apartment blocks. Each building may have several apartments in it, but once one apartment is rented out, it cannot be rented out again to someone else (until the first occupant moves out).

This is where our analogy breaks down just a bit. There is a physical limit to the number of apartment addresses in our mythical city, while in real life, developers would simply buy up another farm. Instead, what we're going to do, through a process called partitioning, is to add another city (and another post office).

There's another way of magnetically dividing the hard drive, called partitioning. Even if a drive is all one piece, it still has at least one partition. But you can have several partitions, and on a large drive, that's a good idea.

How Much Space?

We're going to abandon our analogy now and discuss the effect that partitioning has on cluster size, using FAT32 as our yardstick. In any partition greater than 512 megabytes (MB) and smaller than 8.01 GB, the cluster size is 4 kilobytes (KB). That means that no matter how small a file fragment is, it will occupy 4 KB 

(about 4,000 alphabetic or numeric characters). Even if the file itself is only 1 KB in size, it will still take up 4 KB of disk space. When you go above 8.01 GB, up to 16.02 GB, however, the cluster size jumps to 8 KB. Then it jumps to 16 KB if you exceed 32.04 GB, all the way up to 32 KB for partitions above 32.04 GB. The Windows 9x series (including Me) does not support 64 KB clusters, which is just as well (although both Windows NT and Windows 2000 will).

To cut to the bottom line, partitioning a 40 GB drive into five 8 GB partitions, thereby reducing the cluster size in each partition from 32 KB to 4 KB, will restore to you roughly an additional 30 per cent of the drive's capacity.

Partitioning a blank hard drive with no data on it is relatively simple, but the software that ships with Windows, called FDISK, is destructive. If you partition the drive that came with your computer, all loaded up with software, nothing will be left when you're done.

How you go about partitioning a drive that contains data without destroying it in the process will be the topic of next week's Computer Wares.

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