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Will CHKDSK Harm My Files?

I recently did a CHKDSK scan on two hard drives with video files. The first scanned with no options checked. It did not show any details of progress except the progress bar. It got to the end and then froze (although the computer did not freeze) and the only way to exit it was to shut down the computer or reset. Do you think any of my video files got corrupted or changed in any way? With the other hard drive, I scanned four times without errors. On the fifth time, I scanned it on another computer and it said that it had a file system error. Needless to say, I did not fix that. I don’t know if one of the four times before I checked any options, but I’m thinking I had nothing clicked. Is it possible that my video files on the hard drive got corrupted or changed in any way, even if I had clicked one or both of the options?

You may have problems with your video files, but I don’t think it’s because of CHKDSK. Without any options selected, the CHKDSK utility simply reports the current status of your hard drive.

But there are a couple of interesting things about CHKDSK that I think are worth reviewing here.

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What CHKDSK does

All that CHKDSK does is make sure that the directory or the listing of files on the disk refers to the correct files. In other words, CHKDSK verifies that all of the pieces are there, the data is structured properly, and that everything that Windows needs to maintain that file system is in its proper order.

When CHKDSK discovers that one of these things isn’t right, it reports that as an error.


What CHKDSK does NOT do

The fact that your system froze is interesting, but it’s not uncommon. The freeze is usually because CHKDSK could not recover from an error that it found in the file system. In other words, if CHKDSK freezes, your computer’s hard disk may have a problem.

Before we go any further, I need to be clear: the problem was already there before you ran CHKDSK. All that CHKDSK did was report (or in this case, hang as a result of) an error on the hard disk. In other words, it didn’t mess up your video files.

Something was already wrong with them.

Repairing files

CHKDSK will attempt to repair things if you:

  • Specify the /R or /F options when you are running CHKDSK from the command line
  • Select the “Fix” or “Repair” options when you select it from the GUI

But again, CHKDSK is only trying to repair damage that has already been done. CHKDSK will force the file system to be in a correct and coherent state, and that may result in errors becoming visible in different ways, but this is only only as a result of whatever damage had already occurred.

Where are the errors coming from

File system errors can come from any number of different places. The more common reasons for this are not shutting down Windows properly, experiencing a crash, or having the power removed while the system is running. It’s also possible that the hard disk could be in the process of failing.

The reality is errors happen. Hard disks fail. It’s the way computers work.

The only real way to prevent this from being a serious issue is to back up regularly so that if (or rather, when) something happens to your files (whether they’re video files, data files, or even the files that comprise Windows itself), you’re protected. You have backup copies and you can restore them to the replacement hard drive, the fixed software, or whatever.

But whatever you do, don’t blame file problems on CHKDSK. It’s just trying to help.

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8 comments on “Will CHKDSK Harm My Files?”

  1. Gone are the days of Norton Disk Doctor, a suite of tools that would analyze and attempt to fix just about anything on your PC, all from a nice graphical user interface. I can’t seem to find a modern day equivalent (and no, Norton Utilities doesn’t even come close to comparing). Any insight on a solid, non-invasive, easy-to-use tool that can analyze and remedy disk problems would be appreciated. I want something I can direct my mom to use.

    • Reid,
      Unfortunately I think that computers are just too complex for any program to automatically repair like that. A better idea would be to set her up with an incremental backup system. Then you can at least restore to a previous point when things worked. In the end, that’s the only reliable setup.

  2. Some years ago I was doingsome “housekeeping” on the computer, and deleted some files that I no longer needed. Then I tried to delete the folder and all its sub-folders, but found there was just one folder right at the end of a long chain (all legit) which I simply could not delete. By going in to DOS and fiddling around, I eventually managed to delete the entire chain, right back to the root directory. Fine. Just what I wanted.

    But what (I deduce) had happened was that that folder had been cross-linked. WHen I ran CHKDSK it found an error, and when I told it to fix it…. YES ! It converted every single file in my “My Pictures” folder, and produced seventy thousand different files in seven different folders of 10,000 files each.

    I still have them – this was all on an add-on hard disk, that I have not written to since. Now and again, when the mood takes me, I have go to see if I can retrieve any of them. So far, not a single one have I recovered….

  3. Man system refused to shutdown yesterday and I had to kill the power. After restart the system scanned using CHKDSK. It detected 4 unreadable segments

    Unreadable Segment 6000062-66

    I have noticed using Process Explorer that the system Idle Process is actually using high CPU usage which freezes Windows temporarily. I know this isn’t actually a process but before the problem the System Idle Process ran at low cpu usage.

    (I’ve decided to backup and make an image of my machine due to a prediction that my hard-drive is on its way out)

    Any ideas?

    • If your system is freezing it’s NOT NOT NOT because of the system idle process. It’s not a process, but just an indicator that the CPU is doing nothing – i.e. it’s idle. Something else – quite possibly the hard drive from the sound of it – could be causing your system to freeze without impacting the CPU.

  4. Well honestly, Chkdsk CAN harm your files, as some scans can leave files corrupted afterwards or even delete entire hard drives of data (I experienced this back in 2005, June 1st).
    And back in April this year, several bunches of files were either deleted or left corrupted and unviewable following a sudden boot-up scan (on a large and new 2TB HDD that was becoming unstable being connected inside the PC to my GA-970A-DS3, but did OK when I put it in a USB box).

    Now I wonder what on earth to do with these corrupted files. Tons of PNG’s. They still have the thumbnails when present in that folder. And if viewing them in HEX editors, they don’t consist of 0’s or ‘NUL’ if viewed in Notepad++. But I had no luck trying to restore them with any recovery software that I desperately tried scouring for.
    Not even with CHKDSK itself, which said it was fixing lots of damaged clusters in the very files that are corrupted, after I ran it with a “chkdsk (drive): /f /r” command – and yet no result. Is there a way to fix these from my description?


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