"Prefetch" Folder

[Dean]

Can anyone tell my the function of a folder
named "prefetch"? Tis folder is located at:
c:\windows\Prefetch
This folder currently contains about 95 files that have
filenames like the following:
CLEANMGR.EXE-1F86EA8E.pf
GNSDK.EXE-1074B834.pf

What is the "pf" extension?

I have recently had some applications that are trying to
access the internet and my Internet Security program has
stopped them but I want to determine waht they were and
where they were located on the hard drive. Doing a search
reveled that these program names were in this 'prefetch'
folder.

Thanks
Dean

 

[Rich Barry]

Dean, that's where Xp stores previously loaded files for faster access.
It's a good idea to clean it out once in awhile
so go ahead and delete them all.

 

[Kelly]

Hi Dean,

Added info:

The Prefetcher component in Windows XP is part of the Memory Manager, and
helps to shorten the amount of time it takes to start Windows and programs.

Windows XP "monitors" itself and notices which applications are launched
frequently. It gathers information about these applications and what they
access with the launch and stores this information in the prefetch folder.

It then uses this information to "optimize" access to these files so that
they launch faster.

Once every three days, by default, Windows XP will perform a partial
defragmentation and adjust the layout of the disk based upon current use.
The files to be moved are written in the file Layout.ini (found in the
Prefetch directory under the System Root directory).

More information here on the Prefetch Folder in Windows XP
http://www.kellys-korner-xp.com/xp_p.htm#xp_prefetch

 

[Nick Burns]

I empty my prefetch every month or so. Windows will rebuild it. It is for
booting up faster. But clean it every once and a while. What is .pf pre
fetch.

 

[Alex Nichol]

Can anyone tell my the function of a folder
named "prefetch"? Tis folder is located at:
c:\windows\Prefetch

When a program is loaded, a record is put, or updated, in the
corresponding file in Prefetch, detailing what files it uses, in what
order. Boot of the system has such a record, too

From that two things happen.

One - when a load is started in future, the system arranges to get the
expected files into RAM straight away, without waiting to be asked, and

Two - every three days, a sort of semi-defrag run is done in a quiet
period, which arranges files so that such sets will be able to load as a
smooth stream without need to hunt around the disk for them. The boot
side of this speeds load of the system: the Bootvis program does a
preliminary optimisation of their layout, but it will take place, and
better, through the automatic process. The details of the best layout
are kept in the layout,inf file which is checked and updated each time
this optimisation runs, for the best overall performance. This can be
used for optimisation alternatively by some third party defrag programs,
eg Perfect Disk Pro

Two points:

Contrary to what is said , it is *not* necessary to empty prefetch.
Any program that does not get used for a week will have its file dropped
out anyway: ones that are rarely used get low priority in optimisation

and:
The optimisation at regular intervals is initiated by task scheduler so
you need to have it running for this to work (also for System Restore
to make its daily restore point) even though no scheduled task appears
if you look in control Panel - Scheduled tasks. Check the Advanced menu
there, and if it says 'Start Using. . ' click that so it says 'Stop
using . . .' It then looks for a time when the system is quiescent (I
think it waits for 15 mins of no disk activity, but am not sure on
that). This is one reason for the query 'my hard disk goes chattering
when I am doing nothing'; the other being search engine indexing.

 

[BikeRider]

Thanks so much for your answer. At least I have an idea what's happening
with the files in that folder now.
Dean