CRC File Error

Posted on 2009-06-28
Last Modified: 2012-05-07
I have several files that I can open, and access, but cannot copy - I get CRC errors.  Is there anyway of repairing the error or copying the files to another drive?  Thanks.
Question by:srtechpdccpa
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LVL 16

Expert Comment

ID: 24733986
You could try chkdsk or scandisk however, like any dos file system repair tool you're likely to lose the file, or part of the file.

You say you can open the files but not copy them.... Hmmmm.... When you open the files, can you view the entire file from start to end? If you can then you could try READING from the files and re-creating them however, this will require a program - possibly even a batch file.

It might help us to know what type of files they are ie, text, mp3, images, spreadsheets etc and what their sizes are ie, less than a MB, a few KB, 30B etc (no need to be exact).

Ideally, you should stop using the drive with CRC files as there's a risk of either firther filesystem problems developing or not being able to retrieve as much data then if you were to remove the drive and attach it as a slave drive. that way, you minimise the risk of making changes to the drive itself which could potentially destroy the files altogether.

Once you've re-attached the drive to a PC as a slave drive you can then try some data recovery tools to retrieve your files.

Once you've completed your data retrieval, you're going to have to do a full scandisk on the drive to repair any filesystem errors - this is a destructive repair - meaning, it will normally trash any bad files or at best convert them to CHK type files. Sometimes you can retrieve some data from some CHK files but don't bank on it - and it's not always a straight forward process which I would recommend to novices.

Another thing you may later want to determine is, why did these arrors occur in the first place? Was it due to a failing hard drive - in which case start thinking about backing up alll your data from the drive ASAP. On the otherhand it might have been due to not powering down the system properly for example.

There is much to consider when faced by this situation such as, is the data critical? and how can you minimise further loss right now before you proceed any further?

Please provide feedback.

Author Comment

ID: 24738118
I guess I wasn't thorough enough in my description of the problem, so here are more details:

This is happening on an external USB HD I use to store media files.  The problem started just a short time ago.  I've run chkdsk with the /f switch, and it reported there WERE NO ERRORS with the drive, which perplexes me.  The files are either RealPlayer .RM files or Media Player .WMV files; you can view the movies beginning to end, but if you attempt to copy them to ANY other drive (internal or external USB) you get CRC errors and the file won't copy.  This is not the case with all files; most can be copied.  I've done thorough virus and spyware checks without incident.  I've tried multiple USB ports, as well as plugging the drive into another computer (to rule out any kind of registry problem).

So there it is - hopefully a more detailed description that will lead to a cure...  Thanks t0t0 for your reply - and you don't have to worry about me being a novice - I'm an A+ certified computer consultant, but am stymied as to why I'm getting these CRC errors... there are other types of media files on the drive (MP3's, JPG's etc), however this error is ONLY occuring with WMV and RM files...  Again, if anyone has any ideas, I appreciate the input.
LVL 16

Expert Comment

ID: 24738202
Thank you gratefully for the detailed feedback. Before I delve deeper, could you please say when these CRC errors occur.

Is it only when you attempt to COPY, XCOPY or MOVE them or is it when you play them too in either RP or MP?

Thank you.

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LVL 16

Expert Comment

ID: 24738284
Also, have you tried physically attaching the bare drive to your PC thereby bypassing the external HD interface / USB connection?

I'm wondering if the external HD's interface-to-USB is the cause of the problem. Also, could the length or quality of the interconnecting USB cable be of concern here?

You say you've done a CHKDSK /F and you are still able to play the files from start to end. This is great news. It's also slightly baffling especially i the light of a clean bill of health as far as software nasties are concerned.

Testing on another PC and receiving the same results is good detective work and this only heightens the mystery surrounding your problem.

As I suggested, your next logical approach is to remove the HD from the external box and attach it directly to the PC's internal HD interface.

Please answer the questions in my previous post.

Thank you.

Author Comment

ID: 24738406
Yes - I only receive the CRC errors when trying to move or copy the files; as I mentioned, actually running (viewing) the files presents no problem.  I've tried 2 different USB cables, both of relatively short (3') length without any joy.  I haven't yet pulled the drive from the enclosure, mostly because I don't think the drive or the enclosure electronics would selectively choose specific (and consistent) files to have the problem with.  CHKDSK reports no disk errors (I ran chkdsk on the drive from two separate computers, btw - with the same results), and since I can play the files I assume there is no data issue with them - unless RM and WMV files can play fully even with CRC errors.  So I figured before I went opening computers and drive cases, I'd troll the waters and see if I could catch anything in regards to information maybe pertaining to these types of files that I've not come across yet... but I'm getting close to doing it!
LVL 16

Accepted Solution

t0t0 earned 500 total points
ID: 24739602
I've a feeling your files are corrupt. This may be due to writing CDs/DVDs at higher speeds then the media is suited for.

What you need is a copier that will copy files even if there are file errors. Back in the days of DOS there were all sorts of utilities such as bit-copiers, hex-editors, track and sector-copiers etc.

Perhaps the following is something along the same lines. I don't have faulty failes so I can't try this application out however, it's free so fingers crossed, there's nothing to lose by giving it a whirl.

Author Closing Comment

ID: 31597763
Thanks - don't know what caused the corruption, but the utility you linked me to did the trick; I was able to copy the files to another drive, where they are now completely accesible... don't think I'll know the cause, or the real cure, but it doesn't matter - I got the files!  Thanks for your help.
LVL 16

Expert Comment

ID: 24750784
Well done and thank you for the feedback

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