Power on hours

[taffer]

Hi all,

I have a WD Red drive (WD10JFCX) and I noticed in the SMART data, the power on hours were around 19300 then today suddenly it has jumped back to 18568.

Has anyone ever seen anything like that before? Has my drive gone back in time?

[data-medics]

You should know that when it comes to S.M.A.R.T. values high numbers are always good values. Just think of them all as a countdown to failure. So it's not the actual number of hours it's run, but rather just a value that's counting down the useful life of the drive.

[fzabkar]

I have a WD Red drive (WD10JFCX) and I noticed in the SMART data, the power on hours were around 19300 then today suddenly it has jumped back to 18568.

Very weird. I've seen lots of SMART bugs, but can't recall seeing this one.

[data-medics]

Which value are you actually reading? The RAW value, or it's interpreted value from some S.M.A.R.T. checking software? Perhaps the program you're using is translating it the opposite way of most and giving the remaining time before S.M.A.R.T. warning instead of the already run time.

[data-medics]

I do know that programs often don't know how to interpret this value correctly. For example this hard drive:



Apparently it's been running for the last 34.5years without stop, just a few decades longer than it's actually existed.

[taffer]

I'm reading the raw value, which appears to be in hours as it was zero when I bought the drive and has been incrementing by 1 each hour until yesterday when it suddenly decided to dial back for some reason.

I would expect the normalised value to decrease occasionally but not the accumulated hours raw value.

Strange.,..

edit: attached the smart output

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[fzabkar]

Clearly there is a bug. The raw value must increase monotonically. It should never decrease.

Notice also that the Worst normalised value of 073 is less than the current normalised value of 075. That can't be right.

Code:

Local Time is:    Tue Feb 16 23:00:01 2016 GMT

ID# ATTRIBUTE_NAME          FLAGS    VALUE WORST THRESH FAIL RAW_VALUE
  9 Power_On_Hours          -O--CK   073   073   000    -    19859


Local Time is:    Wed Feb 17 00:00:02 2016 GMT

ID# ATTRIBUTE_NAME          FLAGS    VALUE WORST THRESH FAIL RAW_VALUE
  9 Power_On_Hours          -O--CK   075   073   000    -    18667

[fzabkar]

Apparently it's been running for the last 34.5years without stop, just a few decades longer than it's actually existed.

There is no standard for SMART reporting. It would seem that this particular drive reports the Power On Time Count in minutes rather than hours.

[taffer]

Thanks fzabkar, must be a bug then.

[fzabkar]

Thanks fzabkar, must be a bug then. :)

It could be that the laws of physics are different where you are.