Chkdsk says 400 GB is bad, Data Lifeguard says drive is fine?

Hi, I have two 2TB WD20EARS hard drives installed in a home server. Last night I ran Chkdsk on them, and this was reported:

Disk 1: “170650768 KB in bad sectors.”
Disk 2: “414378904 KB in bad sectors.”

I pulled one of the drives, put it into another PC, installed Western Digital’s Data Lifeguard tools, and ran an extended scan on it. In the morning, it finished and said everything passed. In addition, if you examine the SMART data, everything has green checkmarks and there are no warnings. The Reallocated Sector Count SMART entry shows a value of 200 on both drives and raw data of zero, so I’m guessing that 200 is the default value (but I honestly don’t really know how to interpret SMART values). However, running Chkdsk again reports that high number of bad sectors.

Can anyone comment on what’s going on here?  Why would Chkdsk say 400 GB of my 2 TB drive is bad, but Data Lifeguard says everything’s great and SMART indicates everything is great?

Please help, I’m a little bit freaking out right now. All my data is stored redundantly on these two drives, and I can’t tell if a problem actually exists or not.


Run some other test software like HD Tune.

or hard disk sentinel tests ( registered version only)

Hi, I just wanted to report back to sort of close out this issue.

I ended up finding an error in the event log about my drives suddenly “disappearing” from the system without being properly ejected.  These are internal SATA drives so I don’t know what that was about, but this is how I fixed the filesystem corruption:

CHKDSK [drive letter]: /V /B /X

The /B part is the key – it tells chkdsk to re-evaluate bad sectors and to update its own “bad sectors” tracking file.  After this ran, I had zero KB in bad sectors again.

Vista or Windows 7 is required to use the /B switch.

I replaced the SATA cables just in case they were the culprit, but I’m wondering if there was a power surge or something like that that originally caused the drives to disappear.  Very strange.

Thanks for your help everyone.