What is defragging a hard drive?

Check us out at http://www.vslcomputers.com/

Defragging a hard drive takes fragmented files, files that are split into more than one piece, and puts them together so that the files are in one contiguous piece or chain.

Imagine taking your favorite 300 page book and throwing it up in the air and having all the pages fly all over the place in a shuffled mess.  You could still read the book… it would just take much longer.  When you were done with page 3, you’d have to find page 4 before you could read it.  If we defragged the book, we would be picking up all the pages and putting them back in order.

Files are saved in pieces, or units, onto a hard drive.  The larger the file the more units it has.  Over time, as files are deleted and added to a hard drive, they get split up so as not to waste space… read on.

Image that the first file you ever saved, file1, was 10 units big.  The next file, File2, is 15 units.  File3 is 12 units.

Your drive looks like this:

1111111111222222222222222333333333333

Now you delete file2 from your drive… you are left with file1, 15 units of empty space and file3.

1111111111               333333333333

Now you want to save file4 which is 20 units.  The computer will utilize the 15 units of empty space with part of file4 and put the remaining 5 units after file3.

1111111111444444444444444433333333333344444

File4 is “fragmented”.  After “defragmenting” the drive it would look like this:

1111111111444444444444444444444333333333333

Or

1111111111333333333333444444444444444444444

Either way file4’s units are all put together in one contiguous chain.

A badly fragmented drive can slow a computer down as it would need to read part of a file, lift the read head, find the next piece, read it, find the next piece, read it, etc.  The more it has to do this, the worse your performance will be.

This needs to be kept in perspective though… defragging a drive is a burdensome process.  You don’t want to defrag every time you delete a file or you’ll wear your drive out. 

In Windows XP you can analyze a drive and you’ll be told whether to defrag or not.  Vista and Windows 7 handles this automatically.

Advertisement