Is my HDD still reliable?

[DG25]

I have a WD 6400aaks 00A7B0 (640GB, Blue) hard disk and recently i decided to check its SMART info, to see if it's ok (not because of warnings signs, but just as a precaution). The hdd was working fine in my pc, but the SMART utility showed that it had a warning sign at the "Current Pending Sector" (pic: http://www.imagebam.com/image/791e1495294492). I scanned the surface and HD Tune showed 2 red squares (pic: http://www.imagebam.com/image/ebc49795294658). And finally, i used WD's hdd utility, DLG Diag, which gave errors at both of the tests (quick test pic: http://www.imagebam.com/image/c0296995294948 and extended test pic: http://www.imagebam.com/image/6170c995295115).

So, in the end, i just wrote zeros on it, preparing to send it to RMA. But after the reformat, SMART shows no warning signs, no pending sectors and no reallocated sectors or any other errors. Both DLG Diag's tests pass with no errors and HDD Tune surface test shows no red sectors.

Can anyone explain me what happened? If the bad sectors were remapped, then why it shows absolutely no reallocated sectors (0)? Is my hdd still safe to use for data storage?

 

[[LYL]Homer]

Work at Google on over 100,000 drives has shown little overall predictive value of S.M.A.R.T. status as a whole, but suggests that certain sub-categories of information which some S.M.A.R.T. implementations track do correlate with actual failure rates: specifically, in the 60 days following the first scan error on a drive, the drive is, on average, 39 times more likely to fail than it would have been had no such error occurred.

http://en.wikipedia.org/wiki/S.M.A.R.T.

 

[drescherjm]

Can anyone explain me what happened? If the bad sectors were remapped, then why it shows absolutely no reallocated sectors (0)? Is my hdd still safe to use for data storage?

I had the same thing happen on a WDC black 1.0TB EARS at work. I was running badblocks which found a bad sector at the os level (strange to me I have not seen that in years at work where I have had 100s of drives). On top of the bad sector reported I had a current pending sector. A little while later I realized I was doing a non-destructive read/write test which would take days so I restarted badblocks destructive test (since this was a new drive) and after 1 complete write phase the "Current Pending Sector" went away and there is 0 for all of the other remapped sectors ...

I am going to have it finish 3 more full passes before I decide if the drive is good enough to use in a linux software raid 6.