Why does HD Tune Pro give different results for same drive?

[Tejstar]

A CCTV DVR from a family member has recently stopped recording video, which means playback over the last few days is no longer possible. Watching live video is fine. Hence, I figured that the HDD is likely dead.

The DVR uses a WD Purple 3TB drive and when connecting it to my PC it is still alive so thought I would run a test for errors/bad sectors. The first run on HD Tune Pro gave me the following result:



This left me scratching my head as if the HDD was fine, I wasn't sure what the problem could be (maybe an iffy power supply?) Anyway, before trying to troubleshoot, I thought I'd do another run on HD Tune Pro, and this time it came back with the following result:



This second test was done straight after the first. My question is that, can I really trust HD Tune Pro if on the first run it says the drive is healthy, yet on another test I can see plenty of bad sectors. Why would it give different results in the first place? Anyone have any ideas?

 

[Tejstar]

Ah I see, that would make sense. It does seem that I cannot trust the data.

Thanks for the advice re: smart info for relocated sectors, I'll give that a try.

 

[Tejstar]

I could understand if it did it the other way around (by way of repair/relocating bad sectors). But definitely seems strange to incur at least 7 bad sectors within minutes of running a previous test. I would at least run a third test.

I'm in the middle of the third test as we speak. Will post the results once I have them.

 

[Tejstar]

My third run also reported errors. Think I'll replace the drive and see if it works in the DVR.