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I have attempted to read a bit about chkdsk but I still don't conceptually understand what it does.

From Microsoft: "Creates and displays a status report for a disk based on the file system. Chkdsk also lists and corrects errors on the disk. Used without parameters, chkdsk displays the status of the disk in the current drive."

From Wikipedia: "Displays the file system integrity status of hard disks and floppy disk and can fix logical file system errors."

But this is all extremely vague, and I've not seen a good, concise, clear summary of what is actually going on.

I just ran a chkdsk and got some of the following messages:

Deleting corrupt attribute record (128, "") from file record segment 120759.

The USA check value, 0x0, at block 0x3 is incorrect. The expected value is 0x63.

The multi-sector header signature in file 0x3d5b6 is incorrect.

Deleting corrupt file record segment 251333.

Deleting orphan file record segment 251321.

Deleting an index entry from index $O of file 25.

Deleting index entry P1040158123.JPG in index $I30 of file 118566.

Is there anywhere I can go to make any sense out of any of these messages? Does it matter at all to an end user? Does it ever delete files or only indices? From the log / output it seems like I had a lot of errors in my disk, but don't know if this is something I should be concerned with or not.

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2 Answers

up vote 6 down vote accepted

I think that the Microsoft definition is quite good, from your question-

"Creates and displays a status report for a disk based on the file system. Chkdsk also lists and corrects errors on the disk. Used without parameters, chkdsk displays the status of the disk in the current drive."

From what you have shown, your hard drive basically had a bit of corruption, but it looks like chkdsk was able to fix it.

This sort of thing unfortunately happens over time (bad shutdowns / power failures during writes etc.) and it isn't necessarily anything to be concerned about.

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Does this mean that chkdsk never deletes files? That was a major question I had. –  Cory Jan 28 '10 at 16:45
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chkdsk don't delete files, however it could (partially) recover an already corrupted file to a .chk file. And in case of a serious hard drive failure, the reading/writing can worsen the situation, so the first thing to do is to save important files... –  fluxtendu Jan 28 '10 at 17:17
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Thanks. I'm still not fully satisfied by this explanation, though. "corrects errors" is so vague. Maybe I should just RTFM. –  Cory Jan 28 '10 at 21:09
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@Cory: to really know what errors it can correct this would need a thorough explanation of all NTFS features, data structures and inner workings which certainly is possible but not in a meaningful, short way. Basically, everything the file system takes for granted can go awry, and yes, even with a journal (although that enables pretty good self-healing capabilities); if anything is wrong, then you can try fixing it. Read up a bit on how a file system works and then you can probably think of enough cases where something can go wrong and needs fixing. –  Joey May 2 '10 at 1:17
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Agree with Wil's answer in terms of what the big picture is. You probably don't need to worry what the error messages mean.

That said, if you what the error messages mean, you would need to understand how NTFS/FAT/filesystem of your choosing formats a disk. I think the Russinovich books from Microsoft Press discuss NTFS, and I'm sure there are other free web resources, eg this site seems like a decent NTFS discussion at first glance. But most likely this is more detail than you need to worry about.

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