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124. Checking your disks

By Andrew D. Wright

Dear Mousepad:

I'm having a problem when I run Disk Defragmenter. I get a message that says corrupt file, please run the chkdsk utility. I've asked different people and they have no idea.

Arthur Hooghe
Beaver Bank, N.S.


One of our very cool Chebucto Mousepads is in the mail to you, Arthur, for your question.

On Windows computers files stored on the hard drive can fragment, or be broken into smaller pieces that are stored on different parts of the hard drive. This happens all the time as Windows moves files around and writes the new files in the empty spaces left by deleted ones.

Running Disk Defragmenter every two or three weeks puts the pieces of files together in a more efficient pattern on the hard drive so the computer can read them faster. In Windows XP, go to the Windows Start button then All Programs then Accessories then System Tools to find Disk Defragmenter.

Sometimes though things don't work that smoothly. Files and folders on a hard drive can become corrupted, which means part of the recorded data on the hard drive has been messed up or is missing.

Disk Defragmenter can't risk moving files when it can't be sure what parts of the hard drive are available. To fix this you would run chkdsk, a program that comes with Windows.

In Windows XP run chkdsk by clicking the Start button then click on My Computer. In the new window right-click on your C: drive then select Properties. Click the Tools tab and click the Check Now button.

In the new window that opens click the top checkbox to do a scan and repair of the files and their indexes. Click the bottom button as well to add a full physical scan of the hard drive. The full scan takes a lot longer depending on the size and condition of the hard drive.

The computer will then need to restart. After the Windows splash screen has loaded chkdsk will come up and tell you to press a key within ten seconds if you want to cancel it. Don't press any keys and it will begin scanning your disk.

In the case where a hard drive has developed a bad sector, chkdsk would attempt to retrieve the corrupted data and write it to a good part of the hard drive. It would then mark the bad sector as off-limits for any further writing. It can't physically repair the disk.

In cases where data is scrambled or missing, chkdsk would turn any unidentified file fragments into new files with a .CHK filename. You could open these files with a text editor program like Notepad to get some idea what had been over-written. It is sometimes possible to recover text from a truncated original file.

File scan and repair usually takes less than five minutes to deal with minor file errors while full scans can take up to a few hours.

It's a good idea to run chkdsk every now and again to keep file errors to a minimum and check for bad sectors on the hard drive.

Still running Windows 95, 98 or Me? First stop any excess running programs. Press the Ctrl, Alt and Del buttons at the same time to bring up Task Manager then one by one End Task until only Explorer and Systray remain on the list.

Go to Start then Programs then Accessories then System Tools and click on Scandisk. It offers a standard file system scan and thorough hard drive scan. Click the checkbox to automatically fix file errors and let it run undisturbed. After it has finished come back and restart the computer.


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Originally published 25 January 2008


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