What is Defragmentation ?

[Guest]

Just what good does it do and how do I know when to run it ? I've got
Windows XP if I click on start/all programs/accessories/system tools and then
disk defragmenter, the window says I have 74.5 GB capacity with 59.81GB free
space and 80% free space then I can either/or analyze and defragment Also
underneath there are coloured boxes for fragmented files , coniguous files
and unmoveable files ..what are these ?

 

[Alias]

Do an analysis and see how many files are fragmented. If you have more than
150, defrag even though XP says you don't have to. Before defragging, do a
clean up and chkdsk. Be sure to disable your anti virus before starting the
defrag.

What, exactly, it does, I am not sure. I just know that it needs to be done


Alias

 

[Gee]

Yo, this is the way windows arranges folders and files into continuous
sections. What actually happens is as you use your PC, windows reads from
and writes back to the hard drive. Now if a file is read from one section of
the hard drive and its size is changed for whatever reason, this change
would be written back to a new section of the hard drive. Defragmentation
rearranges all these files together. It make reading files and folder easier
for the operating system.
You can defrag the system once a month but it is really not necessary with
ntfs file systems.

Hope this was helpful

 

[HillBillyBuddhist]

| Just what good does it do and how do I know when to run it ? I've got
| Windows XP if I click on start/all programs/accessories/system tools and
then
| disk defragmenter, the window says I have 74.5 GB capacity with 59.81GB
free
| space and 80% free space then I can either/or analyze and defragment Also
| underneath there are coloured boxes for fragmented files , coniguous files
| and unmoveable files ..what are these ?

fragmentation
http://www.webopedia.com/TERM/F/fragmentation.html

How often you should run it depends greatly on how you use your system.
Monthly is probably sufficient for most home users. If you use programs that
create or modify large numbers of files more often may be advisable. There
is no hard and fast rule, the analyze function will tell you the degree of
fragmentation. If it is constantly high defragment more often.

Third party programs like Executive's "Diskeeper" will handle the process in
the background.

Based on the definition above, "Fragmented, contiguous and unmoveable" are
self explanatory.

--
Doug

I'm not an MVP a VIP nor do I have ESP.
I was just trying to help.
Please use your own best judgment before implementing any suggestions or
advice herein.
No warranty is expressed or implied.
Your mileage may vary.
See store for details.

Remove shoes to E-mail.

 

[Guest]

Hi Madalark,

Fragmentation refers to the condition of disk where files are in scattered
around and divided. The components of some program may be scattered like this
probably due to the modyfying,deleting files. Our OS needs a contigous
cluster of files so we need to defrag the disk at least once in a month.
Otherwise there wasted unnecessary time in searching the scattered components
which makes a process slower.

You can visit this to know how to maintain disk by deffragmentation
http://www.microsoft.com/technet/prodtechnol/windows2000serv/maintain/optimize/w2kexec.mspx

Thouh it is written for Windows 2000 but the needs are the same and process
are similar.

By analyze it means the analysis of the disk condition WRT this
fragmentation of file. It reports you whether to defrag immediately or may be
done later.

 

[R. McCarty]

The disk platters spin and the heads pivot out over the surface to write
or read the data. Visualize a disk drive surface like a cross-section view
of tree's annual growth rings. On a disk drive those rings are called
tracks.
If a file is written to adjacent clusters on a single track then it is
considered
contiguous or a single area of the drive/partition.

When the head pivots out to the track it can read/write the data in one
revolution of the disk platter. If a file is fragmented, say part is on
track
number 28 and the remainder is on track 31 then the head has to move
twice to read/write the whole file. The more fragments a file has, then the
heads have more movements to make to reach it. This is an average time
called Access time. The outer edges of a disk platter are faster, since the
travel time for the head is less. So if you had a piece of a file on Track 1
and the remainder on the last track you have a longer time to read/write
the file.

Defragmentation attempts to move files to adjacent space on the drive.
Fragmentation causes more fragmentation because the disk has not only
pieces of files, but fragmented free space. So when a new file is written
the drive must work harder to find free space to place the file.

Those color bands represent data - visualized from the outermost track
of the drive/partition to the last.

 

[doodle]

Files in your system are stored as a linked list of
‘clusters’ of data on your HD and ideally these shud be
contiguous but file systems can hardly achieve that in a real life
scenario. Frequent creation,edition and deletion of files result in
having to fragment the files and store them in non contiguous clusters
across the HD space.This is called fragmentation. The HD being a
mechanical device has to move its head each time to a different track
instead of reading the clusters in a sequential manner thus causing
slow down of applications.

Defragmentation is the process where the scattered file clusters are
consolidated into a contiguous arrangement thus making the task of
accessing them easier and faster. Faster file access time for your HD
would mean a speed up of actions such as loading of your Operating
System, file transfers particularly for large files, searching of
files, file saving and reading in general.

It is ideal to run a defragmenter on your HD at least once a week
although in some situations daily defragmentation would be appropriate.
It would depend on how frequently files are created and deleted on your
HD. If you are using the Windows built in defragmenter, the 'Analyze'
option will tell you if you need to defragment that drive or not. The
red colored lines stand for fragments or non contiguous clusters, blue
for contiguous (not fragmented) and green for system files. In fact you
can also use an automatic defragmenter instead of the built in one.

 

[Ken Blake]

In

Just what good does it do

Files are written to your drive in units called clusters.
Clusters can vary in size, depending on a couple of factors, but
if your drive is NTFS, you probably use 4K clusters. That means
that any file larger than 4K uses multiple clusters.

If, for a particular file, those clusters are adjacent to each
other on the drive, reading and writing them is as fast as
possible. But if they are spread out over the drive, the
read/write heads have to move to get to all the clusters, and
access to the file is slowed down. That spreading out of the
clusters (their not being contiguous) is called "fragmentation"
because the file now consists of several non-contiguous
fragments.

For various reasons, as time goes on, files that are rewritten
tend to become fragmented (non-contiguous) and access to the
drive slows down. The more you write to a drive, the more
fragmented it becomes. Defragmention is the process of finding
fragmented files, and rearranging the clusters they use so they
are once again contiguous. The result (at least in theory) is
faster access to the drive.

and how do I know when to run it ?

There's no answer that's right for everyone. It depends on how
you use your computer and it depends on how much you use your
computer.



You should defragment your drive when doing so results in a speed
up. Here's what I recommend. Pick some arbitrary interval--for
example once a month. Defragment on that interval a few times,
and assess whether the computer generally feels faster after
doing so. If the answer is yes, defrag more frequently. If the
answer is no, defrag less frequently.



Repeat a few times, and you'll soon settle into a frequency that
works well for you.

 

[cquirke (MVP Windows shell/user)]

On Fri, 5 Aug 2005 04:25:07 -0700, "madalrak"

Just what good does it do

Defragmentation is a "duty now for the future" task, somewhat like
building indexes for faster searches. It attempts to speed up loading
of files, particularly frequently-used files are parts of files.

When a file is created on an empty disk, it has metadata that
describes what the file is, and the data within the file. The data
within the file is created in a single contiguous chain of data
clusters. So already, there is a factor of how long it takes to mode
the drive heads from the metadata to the "real" data.

When a disk volume has been used a while, there will be gaps in the
data space where deleted files used to be. Slowly-gowing files may
start in one part of the volume, but by the time they "grow", other
files may have been saved after them - so to read the file, you may
have to not only mode the drive's heads from metadata to data, but
also from one (oldest) fragment of data to the next (newer), etc.

Defragmentation used to be purely about moving this stuff around so
that all the data clusters of a file's contents would follow one after
the other in a single fragment. All existing files would mbe moved
into one solid mass of data, so as to be close to their metadata,
while all free space would be moved to the "end" of the volume.

But the purpose of defragging isn't really to defrag files and free
space, as I've described - it's to speed up file access, especially to
frequently-used files. Some code files are large, but only have some
parts used frequently, so if we knew which parts, we could selectively
move those closer to the metadata even if this made the entire file
more fragmented. This logic started to be applied in Win98.

While the system is being used, a background service is watching to
see which files, and parts of code files, are being used most often.
In Win98/ME, this info was held in the AppLog folder, but in XP it
takes the form of .PF files in the PreFetch folder.

When you do a defrag, this information is consulted and used to guide
the defragging process on what (parts of) files to put where.

...and how do I know when to run it ?

Firstly, because Defrag potentially reads every file into memory and
writes it somewhere else on the HD, I would never do a Defrag if there
were any doubts about system stability or hardware integrity. It's
like a strenuous workout; makes healthy systems fitter, but can be
fatal to the frail and ill.

Secondly to the above caveat, I'd defrag whenever my volume's contents
have materially changed, or are about to materially change. If I've
just cleared a lot of space (uninstalled some huge app, purged and
curbed a monstrously large web cache, etc.) then defragging is good to
consolodate the free space, etc.

By the same token it may be good to defrag before installing some huge
program, or enlarging the pagefile.

Particularly important times to defrag are after recovering from a
low-free-space condition that has forced new files to be created
within the spaces between other files, instead of in the large
unbroken free space at the end of the volume, and after any sort of
file system or cluster size conversion (volume resizing or conversion
to NTFS). These defrags can be expected to take a while.

Windows XP if I click on start/all programs/accessories/system tools and then
disk defragmenter, the window says I have 74.5 GB capacity with 59.81GB free
space and 80% free space then I can either/or analyze and defragment Also
underneath there are coloured boxes for fragmented files , coniguous files
and unmoveable files ..what are these ?

The legend says what they are. The large red chunk in an NTFS volume
is most likely NTFS metadata as held in the MFT; it's usually
fragmented, and can't be defragged. The large green chunk is usually
the pagefile, which can't be defragged either.

------------ ----- ---- --- -- - - - -

The most accurate diagnostic instrument
in medicine is the Retrospectoscope

 

[Guest]

Well thanks to you all for explaining it to me Seeing as I've never defragged
my computer since I had it, I think it may be a good idea for me to do so now