Deep understanding of WinXP Disk defragmentation system

If you are using a Windows XP operating system, be aware of disk defragmentation issues.

1. Why do you need to defragment?

File layouts on disk strongly affect I/O performance, and files and directories that are heavily fragmented or scattered on disk can compromise performance, although Windows XP automatically redirects certain files to improve performance, but typically this is not part of the system's required routine. And usually contains only a small portion of the file on the disk.

In this regard, you should defragment the disk immediately after the system installation is complete. By default, Windows XP performs a local defragmentation every 3 days and adjusts the physical location of the file on disk based on the day's usage, and the files that are moved are written to the Layout.ini file, which is the Windows XP believes that the physical location of the file on disk should be arranged in this order, and that the path to the file is C:windowsprefetch.

The system automatically collates disk fragmentation when it is idle, reading the contents of the Layout.ini file first, and defragmenting the files involved, which is the basis for the location of the Disk Defragmenter transfer files.

2. An in-depth understanding of the Prefetch catalogue

In Windows XP and its future operating system, the pre read feature (also understood as "preload") is added to improve system performance, speed up system startup, and file read, which are stored in the%systemroot%prefetch directory for *. PF is an extension, and these *.pf files include the details and loading order of the loaded files.

Each application, including the Windows XP startup process, leaves a corresponding prefetch file under the Prefetch directory, which describes the sequence of loading for each module in the application or startup, based on the name of the application's executable file, plus a "-" and describes the hexadecimal value of the full path to the execution file, plus the file name extension. PF, such as QQ.EX-0065A2A1.PF.

Whenever a user starts a program, it automatically leaves a record in the corresponding *.PF file in the prefetch directory. However, a pre-read file initiated by Windows XP always has the same name, NTOSBOOT-B00DFAAD.PF, which contains the record of the file that was loaded at startup.

The next time you start the system or run a program, Windows references the appropriate *.PF file and loads all of the files recorded in it into memory instead of loading the file one by one, as in the past. In addition, Windows uses the *.PF file of the startup program or program to develop an optimized disk allocation scheme, which is stored in the Lyaout.ini file.

3. Do not allow the system to automatically defragment disk

Sometimes, you may find that the function of local defragmentation is very boring, because the defragmentation of the disk will also do some degree of operation on the hard disk. The technique of disabling local defragmentation by modifying registry keys is plausible, but in fact these so-called techniques are completely ineffective.

In fact, even if you delete all the files in the C:windowsprefetch directory, the Layout.ini file will still be created automatically after restarting the system, and the local defragmentation feature will be reactivated 3 days 1 times.

So the correct way to do this is to open the Layout.ini file in Notepad, remove everything from it, and set the file to read-only so that Windows XP cannot activate the local defragmentation feature, and you don't have to worry about C: Windowsprefetch will become bigger and bigger.

4. Further discussion

We can often see from the internet about modifying registry keys to improve the speed of Windows XP, are these techniques really effective? Below, we combine the examples of disk defragmentation to take a closer look:

Question one: Why can't I defragment the C disk?

Windows XP system, when defragmenting the C disk, prompted that the scan could not continue because the C:WINDOWSPREFETCHWMIPRVSE.EXE-28F301A9.PF file was corrupted.

C:windowsprefetch is Windows XP's read-only folder, Windows XP stores frequently used data in the read-only folders, and when you need to use that data again, you can dramatically speed up reading, but as time grows, the size of the folder grows, And there may be some dead-chain files, at which point if you perform defragmentation, you may have the error mentioned above, the solution is to empty the folder, and then defragment.

Question two: Can you defragment the boot?

Windows XP can defragment at startup so that the files that are necessary to start up can be arranged next to each other, thereby increasing the speed at the time of startup, although the feature is turned off by default. The way to activate it is to open Registry Editor, find Hkey_local_mahcinesoftwaredfrgbootoptimizefunetion, double-click the Enable key in the right pane, and modify the key value from the default "N" to "Y".

Question three: Is it possible to improve the startup speed of the system when pre-read is forbidden?

There are 1 tips on how to improve the Windsws XP startup speed on the Web, by modifying the registry Hkey_local_machinesystemcurrentcontrolsetcontrolsession Managermemory The Managementprefetchparameters directory Enableprefeteher the subkey, assigning its key value to "1". This can reduce the pre-read files, reduce the progress bar wait time, the effect is the progress bar run a lap to enter the login screen.

Microsoft's technical documentation explains the implications of Enableprefetcher being assigned different values:

0: Cancel the pre-read function;

1: Only pre-read applications;

2: Only pre-read Windows system files.

3: Pre-read Windows system files and applications, which is the default value for XP.

Although the Enableprefetcher key value is set to 1, it is possible to reduce the prefetch files, but the system initialization kernel is a very complex process, at this time need to load a lot of low-level drivers, boot subsystem and related services, even when we see the Welcome screen, Nor can it be assumed that the system has been started because the system will continue to initialize the loading of the unfinished drivers in the background, although the scroll bars have been significantly less frequent than before, the black screen process before the Welcome screen has increased, so the total system time has not changed.