When I run the chkdsk command on my boot drive, I get an error message "CHKDSK is not available for RAW drives." What does this mean, and how can I fix it?

C:\>chkdsk c:
The type of the file system is RAW.
CHKDSK is not available for RAW drives.

I am running Windows 7, 64 bit. I am not experiencing any serious problems with my machine- this was just a matter of routine maintenance. I know I have run CHKDSK successfully on this machine before, but it has been a long time (probably several months).

  • Do you have multiple partitions? Have you used any software to resize the partition? Do you dual boot? – horatio Sep 14 '11 at 20:37
  • No to all of those questions- just one partition. – JosephStyons Sep 15 '11 at 17:38

"The type of the file system is RAW." means that CHKDSK was unable to determine the file system used on the drive, and considers it to hold unknown data. CHKDSK is made for verifying the filesystem data structures, and it doesn't make sense to verify something it doesn't know which way is correct. (Try spell-checking a text in a language you can't read.)

That the filesystem is not recognized means the "inconsistencies" are at a level beyond CHKDSK's expertise. However, the fact that you are able to boot from said filesystem confuses the hell out of me.

One possibility is that there is some sort of malware (or anti-malware) that is preventing CHKDSK access to the raw disk device. Run a RootkitRevealer scan and see if it shows anything interesting. If you have a Windows 7 install disc, try running CHKDSK from its "Repair" mode.

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    I do have PGP Encryption on this drive. Maybe that's the cause. – JosephStyons Sep 15 '11 at 15:05
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    It probably is, depending on how PGP integrates itself into Windows. (Random guess: chkdsk c:\ ) – user1686 Sep 15 '11 at 15:09
  • I ran full scans with all of the following, and they all reported no issues: Spybot S&D, MalwareDetector, Windows Defender, and McAfee VirusScan. In each case, the application was updated with the latest definitions. I'll chalk this up to PGP for lack of any better idea. – JosephStyons Sep 16 '11 at 20:19

Chkdsk.exe is the command-line interface for the CHKDSK program, which verifies the logical integrity of a file system. If CHKDSK encounters logical inconsistencies in file system data, CHKDSK performs actions that repair the file system data (assuming that the data is not in read-only mode).

This means CHKDSK checks the validity of file systems supported by Windows. This includes FAT16 & 32, NTFS, and exFAT. It does not support any other file system, or raw device.

  • So are you saying that CHKDSK has found "logical inconsistencies" with my data? If so, how can I diagnose and repair that? I thought that was what CHKDSK was for. – JosephStyons Sep 14 '11 at 19:50
  • No, CHKDSK does not work on RAW devices. – Keltari Sep 14 '11 at 20:22
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    I think he is saying that chkdsk thinks the drive's file system is being reported as RAW and therefore, it has given up before it has examined anything on it. – horatio Sep 14 '11 at 20:29
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    +1 to rescue Keltari's reputation. The info is there, but the others may not understand the distinction between a disk and a file system. – horatio Sep 14 '11 at 21:24
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    No -1 votes came from me. Thanks for the answer. I guess the real question is: Why is my hard drive reported as having a RAW filesystem. – JosephStyons Sep 15 '11 at 17:40

If you are using an SD or microSD card and you're ready to remove the files on the card, just get another device (e.g., a camera) and format the SD card there. Reinsert it into your PC and it should work.

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