Windows 7 Hard Drive Errors
Ask Bob Rankin Update, Posted on 2011-02-23
<http://askbobrankin.com/windows_7_hard_drive_errors.html>


Summary: Hard drive errors slow the performance of your computer and may render some data unreadable. Windows 7 includes utilities that can check your hard drive for errors and fix some of them. Here's the scoop on hard drive errors and how to repair them using Windows 7.

Repairing Hard Drive Errors with Windows 7

There are two kinds of hard drive errors. A logical error is one in which data is written incorrectly on the hard drive. The Master File Table keeps track of where files physically reside on a hard drive, the filename, and the size of the file. In some cases, files are stored in chunks that may be scattered over the surface of the drive. The Master File Table keeps track of all those chunks as well.

So what can go wrong? A virus, power glitch or faulty software can trample on the Master File Table, making it think that part of your photo, document or music file is "over here" when in fact it is "over there." This can result in programs saying that a file is corrupted when you try to open it. An error in the Master File Table can also make it appear that a file is gone, when in fact it's just orphaned on the disk.

A physical error is actual damage to a sector of the hard drive's magnetic media; data written to a physically damaged sector cannot be read reliably, if at all. Windows 7 has ways of detecting and dealing with both kinds of hard drive errors.

Checking For Hard Drive Errors

To check a hard drive for errors on Windows 7, click Start and open Computer. Right-click the drive you want to check and click Properties on the context menu. On the General tab, make note of the type of file system you have. It should say FAT32 or NTFS.

Click the Tools tab. Under "Error-checking" click "Check Now." There are two options you can check or uncheck to modify how the error-checking process goes. Each involves a trade-off of time for thoroughness.

When "Automatically fix file system errors" is checked, Windows 7 will attempt to correct any logical errors that it finds. Unchecking this box means Windows will simply report any errors it finds. It's best to leave this option checked, as it adds only a little time to the error-checking process and actually fixes things!

When "Scan for and attempt recovery of bad sectors" is checked, error-checking can take a lot longer. Several hours may be required to thoroughly test every sector of a large hard drive. Windows does not actually "recover" bad sectors; it marks them as "unusable" so that no data will be written to them. Unusable sectors are typically a negligible fraction of a hard drive's total capacity.

Click "Start" in the error-checking dialogue box to begin the scan you've specified. You will have to restart your computer before the scan will run. The scan actually takes place before Windows loads during startup. A utility called CHKDSK.EXE does the error-checking work.

For Power Users: CHKDSK Command Line Options

Running CHKDSK in command-line mode gives you more options than the error-checking dialogue described above. Enter cmd.exe in the Start menu's Find box, but don't press Enter yet. When the little icon with the C:\ prompt appears, right-click it and select Run as Administrator. This will open a command-line window. Now you can enter chkdsk C: (substitute another drive letter if you want to scan a different drive) and any of these command-line options:

  • /F Fixes errors on the disk
  • /V On FAT32: Displays the full path and name of every file on the disk. On NTFS: Displays cleanup messages if any.
  • /R Locates bad sectors and recovers readable information (implies /F).
  • /X Forces the volume to dismount first if necessary.
  • /I NTFS only: Performs a less vigorous check of index entries. (Saves time.)
  • /C NTFS only: Skips checking of cycles within the folder structure. (Saves time.)
  • /B NTFS only: Re-evaluates bad clusters on the volume (implies /R)

So for example, CHKDSK C: /F /R would perform a full scan on drive C: (including bad sectors) and attempt to fix them.

There are very few alternatives to CHKDSK, but if you have a problem that CHKDSK can't fix, try one of these:

SpinRite 6 <http://www.grc.com/sr/spinrite.htm> is one option, but it was last updated in 2004 to work with Windows XP and the NTFS file system. Many people swear by the benefits of SpinRite, but there are two potential downsides. The SpinRite website has a statement that the software may not work as well with modern SATA drives, and it costs US$89.

TESTDISK <http://www.cgsecurity.org/wiki/TestDisk> is a free program that can help recover lost partitions, restore access to files, and repair boot records on disk that have become non-bootable. I have found TESTDISK to be a life saver on several occasions when I thought a hard drive was completely lost, and other recovery tools were unable to fix the problem.

Copyright 2005 - 2011 - Bob Rankin

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