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Three times over the past week or two my laptop (9-year-old Dell running Windows XP Home SP3) has auto-run chkdsk when I've turned it on. The process has taken about 2 hours to complete, after which Windows appears to boot up normally. The chkdsk scans have detected bad sectors on my hard drive. I've made an image of the hard drive and ordered a replacement, but I want to know more about bad sectors.

If the computer can still boot to Windows (which it can), does that just mean that the bad sectors are being marked, the data in those sectors is being relocated and all the files on the hard drive are still fully intact?

Or is it the case that these bad sectors mean that some files have already become corrupted? When I made the image of the hard drive (with Redo Backup & Recovery), it also gave warnings of encountering bad sectors. If I clone the image to my replacement hard drive and corrupted files get replicated to the new drive, I may be missing some critical data and suffer crashes in the future as a result, correct? If that's the case, am I wasting my time cloning the old hard drive to the new one?

Thanks for your insight.

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marked as duplicate by Karan, gronostaj, Brad Patton, soandos, Darth Android Jul 9 '13 at 14:34

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you may want to try ddrescue for taking the image. ddrescue takes some rather sophisticated steps to attempt recovery of the data from back blocks. never any garentees of course, but worth a try if Redo is not sufficient. –  Frank Thomas Jul 5 '13 at 20:24
    

1 Answer 1

Unfortunately, it is as you fear - some files are likely corrupted.

On the other hand, they are probably files that aren't vital: for one, the system still boots; for another, the files that are more likely to trigger a chkdsk are those being written now. Mostly they are your data files, or temporary files, or swap data. There is a possibility of "dormant" files having become corrupt, but in my experience that is very low - unless you wait too much while the disk gives symptoms of impending failure.

Windows system files in Windows XP are "protected" by System File Check (SFC), and discrepancies will be corrected automatically.

So, while you may have lost a little, the key data is very very probably still there, still intact. It is possible, even likely, that you'll indeed have lost nothing.

Imaging the hard disk is still a good and necessary thing to do (think of all the installed programs, preferences, etc.), as soon as possible.

Of course, you needn't be told to keep a copy of important files on another device while the new drive arrives, and not to install any software or make changes to the system in the meantime.

You will restore on the new device the first image you made, and manually copy data files newer than that, which will be the only thing that will have changed.

You will probably want to install a SMART hard disk monitor (e.g. HDDHealth by Panterasoft, but several exist - the latest SpeedFan by AlMiCo has a SMART option) to keep tabs on the new disk.

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It's a pity that when chkdsk finds a bad sector and tries to relocate the data from that bad sector, that it doesn't report whether it was successful or not. At least then you could have a log of corrupted files. Or maybe chkdsk is not able to tell if it has been successful or not? –  osullic Jul 7 '13 at 18:03
    
It can't, or, well... when it fails, it fails. But when it thinks it has succeeded, you can't be sure. chkdsk trusts the hard drive's report, which is "virtual". One can have a closer-to-the-iron view: hdparm does (it even has a --make-bad-sector "VERY DANGEROUS" option). chkdsk doesn't: when it reports OK, anything might have happened: e.g. it could have re-read a zeroed sector from the hot remap HD area :-(. On Linux, I seem to remember (but can no longer find!) a plugin for logwatch that implemented smartmontools.sourceforge.net/badblockhowto.html –  lserni Jul 7 '13 at 19:30

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