Tip #15: Disk partitions, or "I have a C and D drive in My Computer"

A peek in My Computer...

Most Windows computers have two hard drives visible in My Computer, usually named C: drive and D: drive (or E: drive). Often, I hear them say "I have two hard drives" - this is usually not true, if your desktop was just purchased, or if you are using a laptop. In actual fact, there is usually a single hard drive, which contains two partitions, shown as two seperate drives in My Computer.

Imagine that we have a huge rectangular apartment with an area of 320 m² and has no walls, which we can both live in it and use as a store room to keep things. A room this big may be difficult to organise its contents and you certainly don't want to live among your pile of collectibles or junk. To make life easier, we could divide the room into one or more smaller rooms by using wall partitions. I could divide the apartment into two smaller rooms or "partitions", one that is 120 m² which I use as my living space, and the other which is 200 m² which I use as my storeroom (so I don't need to look at the mess all the time). How nice!

The same "principle" applies to your hard disk drive. Suppose you have a single 320GB hard disk (298GB to be exact). We could then divide the disk drive into two partitions, one which is, say, 100 GB for installing the operating system (Windows), and the other 198GB for storing personal files (music, photos, videos) and backups. The advantage to this scheme is that, in the event that you need to reinstall your operating system, you can format only the first partition without worrying that all your personal files will be gone. Backing up will be faster too, instead of burning CDs or transferring to a USB drive, just copy to the second partition and you're done.

If your PC is purchased from an original equipment manufacturer (OEM) such as HP or Dell, and you haven't reinstalled Windows before, you may have a second partition named RECOVERY, which should contain files needed in case you need to restore your computer to its factory state. Depending on whether you have additional recovery media such as DVDs for reinstalling Windows, you may or may not want to keep the files of this partition, or even use this partition at all for storing your own files.

Why did I initially leave out Macs for this tip? Since Mac OS X comes preinstalled on newly bought Macs, and Apple doesn't create a second partition for you, it doesn't really apply to most Mac users (unless you repartition your disk when reinstalling Mac OS X on your own). It applies, however, when using Boot Camp to shrink your current partition and create room for another partition to install Windows alongside of Mac OS X, so that you can dual boot your Mac i.e. choose to boot Mac OS X or Windows into when turning on your computer.

Note: even if your hard drive doesn't have a second partition, it still contains ONE partition which is the one you are currently using. A simple but often overlooked concept.

What I get when trying to eject my external hard drive with 3 partitions...

Partitioning can also be done on external hard drives, however I personally do not recommend this for smaller drives (those which are 320GB or less). From experience I notice that when you have more than one partition on an external hard drive, it is usually impossible to eject (or safely remove) the drive on a Windows PC without restarting the computer. On Macs it would be a few extra steps to eject/unmount all partitions one by one before pulling the USB plug out.