Why Defrag?

When I say that I defrag my hard drive once a week, I am not kidding. All 3 of the computers that I’m using do it every week. I know that so many of the people I have told to do the same don’t, and I figure it is worth the effort to explain why defragmenting is so important.

How Hard Drives Work

What I’m about to say isn’t 100% accurate in all situations, but it’s close enough that this broad explanation of how hard drives work pretty much covers all the bases.

Your hard drive basically has 2 parts to it, a disc (much like a CD) and an arm that sits just above the disc that has a magnetic reader on it. The disc spins around, and the arm moves up and down across the radius of the disc reading information off it as it spins.

Now, let’s look at how a file is read off the disc. First, the arm goes to the table of contents to find where the file starts on the disc. Some files have a “FAT” (File Allocation Table) that stores this Table of Contents, some store the T.O.C. in other ways, but they all pretty much start by figuring out where the file starts on the disc. The arm then moves to the right spot so that when that start position comes around on the next spin of the disc, it will start reading it.

How Files get Fragmented

Now that we know how files are read off the hard drive, let’s look at how they are written.

Let’s say you start a word document. You type into it for a while, and then hit save. The first thing that is done is an entry is added to the Table of Contents on the hard drive for it. At the same time, a starting position is given for the file. The arm then moves into position so that the next time that spot comes around, it can start writing to the disc. But, let’s say that your file is big, and as the disc spins the arm comes to a spot on the disc that is not empty. It can’t simply keep writing, or you would lose the contents of who-knows-what! So, the arm writes in the last spot right before that file a new position, a pointer where the file it is writing will continue. It then moves into position so that when the disc spins around it can continue writing the file at the new spot.

So Why Fragment?

Now let’s look at read the file we just wrote to the disc. You open up your document editor, and ask it to open the file. The arm goes to the T.O.C. to find out where the file starts. It moves into position and starts reading the file when that spot comes around on the disc. But, it c comes to the pointer. It stops reading, moves into position, and starts reading again when the new spot comes around on the disc. This has added to the time it takes to read the file off of the disc.

Imagine now when your computer first starts up. Windows begins loading all of the files needed to run the computer (libraries, device drivers, etc.) Now when you first install windows, these files are not going to be fragmented. Usually, you install windows onto a clean hard drive, so the fragmentation thing doesn’t come into effect. But, as time goes on, you run windows updates (I pray) and maybe some of these files are updated… The old ones are deleted, new ones are written. New ones could be bigger or smaller. Fragmentation occurs.

Many of the activities you do on your computer on a day to day basis cause fragmentation as well. Just browsing the web creates temporary files (cache), cookies and many other files that will get deleted over time, creating fragmentation.

Ok, I’m convinced. How do I defrag my hard drive?

Good Choice!

Windows XP Users:

1. Left Click Start
2. Left Click Run
3. Type dfrg.msc in the “Open:” box
4. Left Click “OK”
5. Don’t Have Run? Do this:
   1. Open My Computer
   2. Right Click on your “C:” drive
   3. Left Click on “Properties”
   4. Left Click on the “Tools” tab
   5. Left Click “Defragment Now…”
6. Left Click on your “C:” drive (it should be the first one on the list.)
7. Left Click the “Defragment” button
8. Let it run and do it once a week!

Windows Vista Users:

1. Open a Command Prompt as Administrator:
   1. Go To Start
   2. All Programs
   3. Accessories
   4. Right Click on “Command Prompt”
   5. Left Click “Run as Administrator”
      (You will need administrator privileges to do this.)
2. Type defrag c: -w
3. Let it run and do it once a week!