What is... A Hard Disk Drive

A guide to understanding Hard Disk Drives

Author:  Paul Landers

A Hard Disk Drive (usually referred to as HDD, commonly called storage, hard disk, hard drive or any combination thereof, at times referred to as your "C" drive) is a permanent data storage medium. The HDD inside your computer functions similarly to a filing cabinet in an office. Information (data) on a HDD is stored in files and files are stored within folders. Like a filing cabinet in an efficient office, files are "taken out" of the HDD, worked on in RAM (memory) and then "saved" back to the HDD when done. 

Hard Disk Drives come in the form of a fully sealed metal enclosure. Inside the enclosure is a "spindle", upon which is mounted 1 or more metal platters (which look rather like small metal CDs). Information is magnetically encoded onto the platters via corresponding "heads". The Heads, attached to an "arm", move in an arc, slightly above the surface of the platter, to "read" and "write" to the platter/s. You may have heard the term "Head Crash" with reference to a Hard Disk Drive - it means that the Read/Write Head/s literally collapsed onto the surface of the platter/s, scratching the platter/s and rendering the Disk useless. A Hard Disk Drive is classed as a permanent storage medium, ie. the information magnetically encoded to the drive remains there until magnetically removed.

Inside a Hard Disk Drive enclosure

A Hard Disk Drive can be "partitioned", meaning that it is formatted so that your computer sees it as 2 (or more) Hard Disk Drives. This is done for many reasons, most often to keep program files and information files separated, thereby keeping the Hard Disk Drive tidier. 

The HDD is accessed via your computer's Operating System which maintains an "index" of all the contents of the Drive so as to access them quickly. When you delete a file or folder, the deleted contents are not actually removed from the HDD. Instead they are marked as deleted and, in due course, when that space is needed, the deleted information is simply overwritten. That is why deleted contents of a HDD can be "recovered" (provided they have not been overwritten with new information) using commonly available software utilities.

A Hard Disk Drive plugs into a board in your computer and can therefore be (relatively) easily replaced and/or upgraded. These days, most new computers are sold with at least 30 GigaBytes of Hard Disk Storage. You can find out more about GigaBytes here. Unless you're collecting a lot of large files (music and/or video files are very large), you shouldn't need to upgrade to a larger capacity. Everyone's needs are different though, and horders (like me) will soon accumulate a lot of information that they are reluctant to "delete" or part with. In this case, chances are that you will need a larger capacity of Hard Disk Drive and/or and external Hard Disk Drive. If you do upgrade and/or replace your HDD, it's important to remember that HDD speed is measured in "access times" of milliseconds - smaller numbers of milliseconds mean faster access (or quicker disk).

Over time, your Hard Disk Drive accumulates a lot of junk (and I'm not talking about the information you're  hoarding). This "junk" comes from a multitude of sources - file fragments being left behind by various programs, temporary system files that never get deleted, bits and pieces that get omitted from deletion, etc etc - the list is endless. While these bits and pieces individually don't take up a lot of disk space, combined they add up to many megabytes. Worse, they "fragment" your hard drive because they often reside in spaces in-between important information (picture a messy filing cabinet cluttered with scraps of paper that have long since become obsolete and mean nothing to anyone). A "fragmented" Hard Disk Drive" slows your computer down (because valid information is more difficult, and takes longer, to access). Quite simply, your Hard Disk Drive needs to be cleaned and maintained regularly to ensure optimal performance.

In the meantime, look in your Programs (click on Start then on All Programs), under Accessories (we're talking Windows XP here) you will find System Tools. Under System Tools you will find a "Disk Cleanup" utility (or program) and a "Disk Defragmenter" utility (or program). They're not as good as some of the commercial ones, but they're a good start... and they're free. Go ahead, start your computer spring-clean today, you'll notice the difference. Make sure you "clean" before you "defragment".

Additionally, the important contents of your Hard Disk Drive MUST be "backed up". Backing up simply means taking a "copy" of the important contents and keeping that copy somewhere other than your Hard Disk Drive.

What do we use to backup our computers? We use a program called Zip Backup. It's inexpensive, fast, easy to use and has everything we need and more. If you're looking for backup software, we highly recommend Zip Backup. You can find out more about it and/or trial it here.

You can read a more detailed article about maintaining and cleaning your computer here.