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Summary: CRC errors happen when there's a bad spot on the media of your hard disk. Data recovery and disk repair are often possible with the right tools. Outlook started acting up, so as part of my attempts to fix it I tried to copy the PST to another location. The copy failed part way through with a cyclic redundancy check error. How can I get past this and backup my data? The cyclic redundancy check or "CRC" error indicates a bad spot on your hard drive. The fact that you're seeing it when you try to copy a file indicates that the bad spot may be within the file itself. We need to verify that, and then we need to try to recovery your file and repair your hard drive. • First, let's make sure that the problem is actually with the file you're copying since it's equally likely that the problem is with the location you're copying too. This is easy. Fire up a Command Prompt window, and then copy the file to NUL: Microsoft Windows XP [Version 5.1.2600] This reads the entire file by copying it "nowhere". If this succeeds the problem is not actually with the file itself, but the location you were trying to copy it to. My recommendation would be to copy it to a different disk entirely, or a different machine on your local network. If this copy fails, then we've confirmed that the bad sector on your hard disk is actually being used by some portion of your file. • Now that we've confirmed that the problem is in fact in the file itself, we need to make as best a copy of it as we can, somewhere else. This sets a position of "it can't get any worse than this". Some data within the file may be lost, but you'll have copied as much as possible before the recovery efforts. Once again, we want to copy the file to some different hard disk, or some other machine on your local network. And once again we need to do this within the command prompt: Microsoft Windows XP [Version 5.1.2600] Two important things to note here: we've used the xcopy (for eXtended copy) command, and we've added the "/C" switch which keeps copying even if errors are encountered. As you've already experienced, the default behavior of both COPY and XCOPY is to stop if an error occurs. Now that we've got a "no worse than" backup copy, we can start attempting to repair the disk. • If you're willing to spend $89 (as I write this) then there's a very good chance we can simply repair the hard drive. I'm a huge fan of SpinRite. SpinRite is a hard drive recovery and maintenance program. When you run it it will perform a lengthy and exhaustive analysis of your hard disk without modifying its contents. Exactly how it does what it does is probably too technical and lengthy for this space, but one of the most important things that it does is simply this: If a bad sector can be recovered, SpinRite will recover it. And many, though of course not all, bad sectors can be recovered using SpinRite. The net result is that after running SpinRite on the drive, it will either recover the sectors and you'll have a good, working hard disk once again, or it won't - and you'll know with some confidence that the disk cannot be recovered. In the first case; if SpinRite is actually able to recover the sector for you, then unless SpinRite tells you otherwise, I'd then happily reboot and continue using the hard drive. If SpinRite is unable to recover some data on your hard drive, I would first reboot into Windows and, as we did above, make another copy of the file. While SpinRite may not have recovered all the bad sectors on your hard drive, it could have repaired some, and those might have been the ones causing the problem with the file you're trying to access. I would not overwrite our first "no worse than" copy, but I would save this new file, as a kind of "possibly better" copy. And then I'd plan on replacing the drive. • If you're not up for spending the money for SpinRite, then Window's own CHKDSK utility is the next best thing. It's not as thorough, and it doesn't perform the same deep analysis and recovery as SpinRite, but it can, in fact, recover from some types of hard disk failures. Once again, in the Comment Prompt: Microsoft Windows XP [Version 5.1.2600] The "/R" parameter indicates that CHKDSK should check for errors and repair them as best it can. Important: if this is your system drive (most often C:), this command will not actually run the operation immediately, but will schedule it for the next reboot. You'll need to reboot to actually make it happen. After it's done, try making another copy of the file. If it doesn't work, then obviously CHKDSK wasn't able to repair the error you're experiencing. If it does, however, save that copy as a possibly fixed copy of your file. Even if CHKDSK does repair the problem, I'm actually torn on how much to continue to trust the hard disk. You could still experience future failures. Though I suppose that's true for any hard disk, after any utility is used. Or not. • At this point, if none of the steps above have repaired the bad sector or otherwise recovered your file, you're just a little bit screwed. It's now time to work with the best-effort file that you saved earlier and, depending on what kind of file it is, try to recover the contents. In your example, an Outlook PST file, that means running scanpst on it, which will scan the contents of the file and attempt to recover what it can. There most likely will be data loss. Sometimes a lot of data loss. That's why I encourage you to never run utilities like scanpst your only copy of the file. You always want the original to go back to in case there's something else in it that you can recover manually. For other types of files and applications, it'll depend entirely on the specifics of that application as to how it will deal with a partially corrupt file, and whether or not it can be repaired. • And that brings me to my last point. If this was your only copy of the file - if you would have suffered significant data loss had this file become corrupt - you haven't been backing up. Start. This was a wake-up call. Even if we successfully recovered your file, you should be very scared. Start backing up your important data. Now. The next time there's a problem, you may not be as lucky. Related:
• Recent Comments
Just quick message to Rob, I would start to break out that PST into several, perhaps by year. In my former life as an admin, I know that when you start to approach 2gb size in PST files they tend to corrupt very easily. Also, thanks for the article, it was helpful Posted by: Mark at January 27, 2008 09:52 AMI purchased a program that has an application CD and an application update CD. Then there are 6 CD's that install the data. Mostly .cab files that contain large single files that are spanned. When I get to the 5th CD, there are two cab files. one contains the remainder of the 4th CD spanned cab file and the beginning of another cab file that spans to the 6th CD. When installing, the 5th CD stalls just before the end of the cab that flows into the 6th CD, but then it pops up a window that says installation complete. it doesn't ask for the final disk and I can not access any of the data or the program at all. If I try to copy the cab or extract the file it contains, I get Cyclic redundancy error. If I copy it from cmd prompt with a c switch, it still errors CRC because it's all one big file. I tried an error fixing program that got through the file transfer to HD, and I burned it to a new disk, but it still is premature installation and won't work. The file in the cab is called rfile002.001 and spans data5.cab (disk5) and data51.cab (disk 6). any ideas? I know it is the 5th disk and not my drive. Posted by: Anthony Terlicker at February 9, 2008 05:33 AMDear Leo, I have 1 disk 2 partitions. Back-up C: to D: with Ghost works fine. Have done it multiple times. Also Wondows / properties / Chkdsk does not find a problem. This would indicate no problem with the hard drive. Ran “ignore bad sectors” and it seems to work. Tried using Nero-7 backitup, still copies to multiple DVDs then fails with CRC error at the end. So disk to disk works, but disk to DVD fails on two DVDs in the same manor and after creating first 3 DVDs correctly but on the end of the 4th. If it’s the hard drive, why would it work disk to disk. If it’s DVD, why always on last DVD and on different DVD drives. Should I be looking at cable, mother board, etc. I have not tried to connect the DVD as a secondary drive on the first IDE cable yet. Many thanks, Thanks for the tips! My users OST file was corrupted and I could not copy it to "null". Since we are lucky enough that we keep it on the server, I was able to delete his ost file and it re-created itself when I reopened Outlook. Posted by: Jen T at April 9, 2008 12:02 PMhello im loreous, i was downloading a file, when it was almost finished a error will come.. CRC error.. what should i do?? please help Posted by: loreous at May 26, 2008 09:22 AMhi, i reached the xcopy section of this article but it deont seem to work .. it cant copy the file form the cd to the hard drive ! i have a game there is the data4.vis file that is causing the problem and it cant copy it to the hard thats where i am stuck any help ? Posted by: RICHO at June 7, 2008 07:23 AMHello leo. i copy a folder from cd to harddisk.some files didnt copy a crc error msg appers.how can i copy from the datas from cd to harddisk Posted by: shanmugavel at July 11, 2008 12:10 AMI am trying to copy one of my VCD from cd drive to my local hard drive. Its giving me error "Cyclick redundany check" and stops the copying. Can i still get my data back or its lost? At times a file or software being downloaded from the internet may get corrupted . The corrupted file or software will not work and will give the cyclic redundancy check data error when one tries to delete it from the hard disk. Running CHKDSK can help in deleting the file or software completely. Posted by: M P Singh at August 21, 2008 08:12 PMPost a comment on "How do I fix a cyclic redundancy check error when I try to copy a file?":
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