I have been told that defraging doesn't actually do anything on NTFS, what
do you think?
Run a defrag application and see for yourself.
There has been two camps, to defrag or not to, ever since there were
computers. All hard drives are arranged in sectors. There are virtual
regions created during formatting that Windows uses to store files. A
sector holds X amount of data and/or slack since a sector in use must
be filled, it can't be half empty. Right click on almost any file,
then properties, then look at the details. You'll see two important
values. The size of the file itself, and the space it takes up on your
hard drives which is ALWAYS larger. How much larger depends on the
file size and the size of your sectors. For example if you have a file
that's 4,100 bytes and you have 4,096 byte sectors, this will require
two sectors of your hard drive with almost an entire sector being
wasted to store such a file.
Example: I went to the Windows folder, and just picked a file at
random. Explorer says it is 802 bytes and takes up 4,096 bytes or 1
sector on my root drive. The difference between the actual space used
to fill the sector and the space the file data actually takes up is
called file slack. Windows by itself fills slack with old file
fragements, junk from paging files, etc.. A GIANT security hole, but
that's beyond the scope of this post.
Now that's a little file. Larger files can span many sectors. For
example a large image or video file can span thousands of sectors. If
the sectors used to store the file are uninterrupted meaning they
follow one another, like on a brand new hardly used hard drive then
your hard drive's read/write heads hardly have to move to find the
data you asked for and bring it into memory.
However over time files get fragemented, ie Windows uses random
sectors to store parts of files. Over time more and more files get
broken up to be stored in different sectors all over your hard drive.
Only Windows, not you, know which sectors get used to store any
particular file. This information in FAT32 systems is stored in the
File Allocation Table (FAT). In NTFS file systems there is much more
than a mere table. Everything is journalized with metadata and
indexing, again beyond the scope of this post.
When Windows needs to retreive a file it first looks up where it put
all its pieces then one after another reads from the sectors the file
is stored in. If the file is contained in more than one sector, which
is very common, it needs to move the read/write head of your hard
drive to get it positioned over the correct sectors. We've all heard a
hard drive clicking away madly which often happens when files are
scattered all over since the hard drive now has to jump back and forth
to file all the segments stored in the many sectors used. Over time as
files get more fragemented this can cause Windows to slow down and
more importantly put more ware and stress on one of the few physical
parts of you computer that has moving parts (your hard drive) which it
turn can make the read/write heads drift out of alignment and sooner
or later be unable to read some of your data.
Getting in the habit of defraging your hard drives restores most files
to use ajoining sectors and greatly reduce or eliminate
fragementation. The counter argument is the process of defraging
itself puts a lot of stress and ware on your hard drive. If you get
obsessive about it, maybe. Suggesting NTFS drives don't get
fragemented is simply not understanding the process of how data gets
written and read from your hard drives which is why I explained
briefly how it works.
