Hi there,
I've got a Hitachi HTS725050AE630 500GB 2.5" SATA III laptop hard drive and I'm having the most interesting situation with it. The S.M.A.R.T. status shows the following as of just a minute ago (and I'm not 100% positive this image is going to display properly):

Now here's the strange thing: that hex amount for the 04 Reallocated sectors count (0x13909D8) works out to
20,515,288 bad sectors so obviously that's quite alarming, especially for a Hitachi/HGST drive as I've never
ever had a Hitachi/HGST drive go bad on me let alone develop even 1 bad sector and I've owned quite a few of these drives over the past decade, I have a 1TB version of the same drive in another laptop, no problems.
I've run the following checks and tests on this drive:
- IBM/Hitachi Drive Fitness Test (the diagnostic from the maker of the drive and what I consider to be the one truly trustworthy diagnostic for it): no bad sectors detected, S.M.A.R.T. status doesn't throw up red flags, disposition code is 0 for both the short and long tests
- MHDD: no bad sectors detected, S.M.A.R.T. status shows the same for the bad sector count, did a full end to end F4 scan with erase write delays and got not one single issue across the entire drive
I've done both the DFT and MHDD scans not once, not twice, but three times in the past two days and again those two diagnostics cannot find a single thing physically or mechanically wrong with the drive but the S.M.A.R.T. status with that 20,515,288 bad sectors somehow is a concern for me.
As stated, I trust Hitachi/HGST drives above all others, they are the one brand/OEM (and yes I know it was originally IBM then the manufacturing turned over to Hitachi and then that became HGST) that has never failed on me as already mentioned so, I'm going to continue using this drive even in spite of that S.M.A.R.T. status. To be honest I don't trust S.M.A.R.T at all - I've got a shoebox full of Western Digital drives from clients where they are mechanically dead but the S.M.A.R.T. status was green/all clear even after they failed as the case was.
Just wondering what other people think about this situation because it's a bit baffling to me. I know technology can and does fail quite often but this is the first time I think I've ever seen S.M.A.R.T. fail so colossally at least in my opinion - it's been at the 20,515,288 bad sector count for a month now and the drive runs basically 24/7 in my Wife's laptop which never shuts off or goes into sleep mode ever and runs sometimes for months before a reboot without issues. Because it runs 24/7 that's one reason I only buy Hitachi/HGST storage media for us, actually.
Odd situation...
