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Two days back, I had to power off my laptop (by long-pressing the power button) due to frequent power fluctuations. I am unable to boot into Windows 7 since then (it automatically goes into recovery mode). But I am still able to boot into Windows 8 installed on another partition of the same drive (dual boot).

From Windows 8, I tried to do the "Error Checking" on the Windows 7 partition (Drive Properties -> Tools -> Error Checking). This operation just gets struck at some point and doesn't move ahead.

So my question is, will I be able to format this particular drive, reinstall Windows 7 and safely use it like before, or has this drive become useless?

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migrated from Oct 23 '12 at 13:00

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Download the hard disk manufacturer's test utility and see what it has to say about the drive. – Karan Oct 23 '12 at 13:04
@Karan, it fails the HDD Confidence test (and few other HDD related tests). But as I already said, I can boot into Windows8 installed on the same HDD. So, HDD isn't DEAD for sure. Infact, except for the windows 7 partition, all the other 3 partitions are working just fine. – Srikanth Reddy Oct 23 '12 at 13:09
"But I am still able to boot into Windows 8 installed on other drive" - Now I am confused. Is Win8 on another physical drive, or on another partition of the same drive that Win7 is on? Also, as Craig noted below, even if the drive isn't dead it looks like it could very well be dying. Get your important data off it ASAP! – Karan Oct 23 '12 at 13:11
@Karan My mistake. Windows 8 is on a different partition – Srikanth Reddy Oct 23 '12 at 13:29

Before you do anything else, if you have any data of value on the system, disk image the hard drive in case it is failing. You can do this from numerous different bootable utility CDs, most of which can write a disk image to an external USB hard drive.

Next, if it's a spinning magnetic hard drive not an SSD, do a S.M.A.R.T. self-test on the drive. If this passes, there's a good chance the drive is OK. Do not rely on the SMART self-reported health check, this frequently reports "PASSED" on drives that're moments from total failure. Again, numerous utilities for Windows SMART testing are available.

If the SMART test passes you probably have either a damaged operating system install or file system corruption and - if there's no data of value on the system - can reformat the damaged partition and reinstall. You might want to try booting off the Windows 7 recovery disk first, as it might be able to repair the system without reinstalling. Be aware that re-installing Windows 7 or using the recovery mode of the install disk may break Windows 8 by replacing its bootloader, forcing you to repair Windows 8 before it'll boot.

You should not get file system corruption due to crashes and power-offs. If it's happening, there's something not right with the machine. If your system has an SSD it might not have proper power protection for its write-back cache and might not respect disk flush requests - this is true of many cheap consumer SSDs. Such disks can never be truly reliable, and should only be used if you keep good backups.

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I have already moved all my data to my external HDD. I did a few Harddisk tests using utilities disk provided by DELL and most of them fail including CONFIDENCE test. But, booting into windows 8 installed on other partition, I am able to use all the other 3 partitions (except windows7 partion) as usual without any errors. Just for the windows7 partition, when I try to copy a few files or try to do "Error Checking" system seems to crash/not-respond. In such case, can I safely format that particular drive and reinstall win7 and use it as usual? or is that partition damaged for ever? – Srikanth Reddy Oct 23 '12 at 13:26
Well, if the disk tests fail then I'd be reluctant to rely on the disk; it's probably going to get worse. Consider replacing the hard drive. – Craig Ringer Oct 23 '12 at 13:40

I suggest you try out this software here as a boot-cd:

It will show you quite clear, if and where your harddisk might have defect sectors, and it might even be able to move them away from your active partition, restoring basic functionality.

However, depending on the results of bad/weak sectors detected by MHDD, I would rather suggest, that you replace this drive as soon as possible.

To restore your Windows 7 there might be some ways - with XP there was some recovery-mode to replace basic system-files.

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