David Brown wrote
MS doesn't say defrag is necessary - but they do make weekly defrags a default setting for Win7 (assuming the OP was
correct there).
Yes he is on that point.
They certainly make defraging easy to do.
But does that mean it is actually /useful/, either in reality or in
the minds of MS?
No, of course not - all it means is that customers /think/ defragging
is useful, and expect it to be easy and automatic. Whatever one may
think of MS and their software, they do listen to customer expectations.
Users of Windows, and DOS before them, have learned to see defragging
as essential - so MS gives them that.
Its a bit stronger than that, some of the MS KBs do say its useful.
Doesnt mean they are right tho, or that they do any more than proclaim that.
There was a time in the DOS and Windows world when defragging /did/ have a significant impact. DOS and Windows (even
the latest versions) have never been very good at file allocation,
Its been much better lately.
so there has always been more fragmentation than necessary. When combined with small and badly designed disk, file
and directory entry caches, this meant that fragmentation lead to a great deal more head movement
Thats overstating it.
and disk latency than was necessary - defragging, and other disk optimisation (such as placement of files and
directories) could have a measurable difference.
And ever since XP, its done that stuff auto too.
But modern machines have much more memory, and newer windows versions are better at using it as cache - greatly
reducing the head movement and the impact of fragmentation.
And large files dont fragment anything like as much either.
(This is the main reason why there have been very few defrag programs for non-Windows systems - *nix systems have
always been far better at using memory for caches,
And have been more vulnerable to power failures etc too.
as well as having better allocation policies in the first place, so that fragmentation has never been a big issue on
*nix.)
And they havent been in Win for a long time now.
Even at its worst, you might find an impact of perhaps 5% on reading large files
Its nothing like that in practice, essentially because there isnt much
linear processing of large files on modern systems except when
playing media files and with that situation, a few extra seeks during
the linear movement thru the file is literally completely invisible.
Even with the transcoding of large media files like video where
you do move linearly thru the file, so much work is going on in
the transcoding that you dont see anything like the transfer rate
that the hardware can do, so again, extra seeks are invisible.
And the system is normally doing extra seeks anyway just because
few use a system for just the transcoding alone so the heads are
moving around because the user is doing other things while the
transcoding is happening, if only catching up on the news or mail etc.
- but if it takes 10 seconds to start a big program or open a large file,
Anyone with even half a clue doesnt close those once they are opened
so that only happens just after a reboot that doesnt happen often either.
with a variation of +/- 20% due to other factors (other programs, anti-virus, automatic updates, network delays, etc.,
etc.), then the fragmentation overhead is lost in the noise.
Yep, completely invisible to the user.
Even with hibernation to the drive, where you do see linear processing
of quite a large file, a few extra seeks isnt even visible either.
No one is saying that file fragmentation does not have a performance impact - only that it is rarely noticeable or
measurable in real life.
The myth of defragmenting being "essential" is hard to kill - there
are too many companies making good money from selling basically
useless defrag programs that do nothing that cannot be done using the inbuild Windows software (or totally free
alternatives). Such companies put a lot of effort into their marketing to keep these myths alive - and to spread them
to other platforms.
There /are/ situations when defragging can be helpful - such as if you deal with a lot of large files.
Hardly ever even if you do. I have a hell of a lot of very large files
but they are what the PVR has produced and even tho I do process
them a bit, to delete what I have watched from an entire evening's
capture of a particular TV channel, a few extra seeks arent even
visible, because only a fool hangs around twiddling his thumbs
waiting for the edit to happen etc.
Ditto with backups which do involve very large files, the time
is dominated by the backup op, not by head seeks and again,
only a fool sits their twiddling their thumbs while a backup happens.
But it is essentially useless on a busy filesystem with lots of small files and lots of deletions (especially on
Windows, due to its poor allocation policies)
That hasnt been true for a long time now.
- even if defragging helped noticeably, your new files would be fragmented shortly afterwards.
Fraid not, even on the PVR which does write a hell of a lot of very large files.
If you have a separate disk (or partition) used for storing large files that you need to access as fast as possible,
then it may be worth the effort defragmenting that on occasion
Nope, even on the PVR.
Not even yearly.
).