Is CrystalDiskInfo's "power on hours" reading accurate?

[mikeymikec]

I re-set-up my system recently with a new SSD and 1TB HDD.

The HDD initially would have had more time switched on because I backed up data to it before starting the work via a docking bay but I'd say it ought to have had a maximum of 3 hours more than the SSD at the point that I finished setting up the system with the boot SSD.

Since then I played with power saving settings a bit to not so aggressively power down the HDD, and I know it's being powered down because I can hear it spin up on the occasion that I request something from it.

However, the 'power on hours' reading for my SSD is 193 hours, and for the HDD it's 221 hours! It would make a lot more sense IMO if those figures were the other way around. The 'power on count' is the same for both devices, which makes sense I think.

I suppose that it's possible that my SSD is being powered down, but I can't remember the previous setup ever powering down the old HDD because I didn't ever hear it spin up (presumably because if it was the only disk in the system, data would be required often enough that it wouldn't be allowed to power down).

 

[DominionSeraph]

Spun down may still count as power on for SMART purposes.

 

[mikeymikec]

That's sounds like a reasonable theory (when a HDD is spun down, it probably still has some power going to it). Even then though, there's still a discrepancy of about 25 hours.

 

[WilliamM2]

No it's not always accurate. I have an SSD that's a little over a year old showing 6404 hours. I also have a pair of 500GB Samsung drives that are both from the fall of 2007, bought about a month apart. One shows 5843 hours, the other shows 28564 hours. The drives are the same model, with different firmware. HD Sentinel give the same exact results.

I have always had my computer set to not spin down the drives.

 

[mikeymikec]

Hum, I wonder how it gets such screwed up readings.

 

[Charlie98]

I have an Agility3 and a 840Pro... both read what I would call realistic power on hours in CrystalDisk... but my Plextor M5P does not. The M5P has been in use since OCT'13 almost 24/7, but only shows 489 hours or roughly 3 hours a day... not true at all.

I've often wondered if it's some tricky way to get a better MTBF count...

 

[mikeymikec]

I've often wondered if it's some tricky way to get a better MTBF count...

Since MTBF is measured in a specific way that doesn't allow much room for nonsense (AFAIK), wouldn't this be a very dodgy practice that could land them in hot water legally speaking?

 

[Charlie98]

Since MTBF is measured in a specific way that doesn't allow much room for nonsense (AFAIK), wouldn't this be a very dodgy practice that could land them in hot water legally speaking?

Unless there is some other hidden power hours reading available, how else could they determine total hours? The very lame Plextor toolbox shows the same hour reading as CrystalDisk, et al.

 

[mikeymikec]

TBH I have no idea how MTBF is measured I assume that there must be a way to produce the figure, and that way must stand a bit of scrutiny legally.

 

[BarkingGhostar]

I believe they use an artificial method to condense many years worth of use down to a short period of testing. How this is done is unknown to me.

 

[corkyg]

Does CrystalDiskInfo get its data from S.M.A.R.T.? If so, then it is no more accurate than the source.

 

[mikeymikec]

Does CrystalDiskInfo get its data from S.M.A.R.T.? If so, then it is no more accurate than the source.

Apparently. 'Power-on hours' and 'Power-on count' are both SMART readings:

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

Also, which I thought was interesting:

"On some pre-2005 drives, this raw value may advance erratically and/or "wrap around" (reset to zero periodically)."

Chasing that source:

"On some Maxtor disks, the raw value of Attribute 9 (Power On Time) is supposed to be minutes. But it advances at an unpredictable rate, always more slowly than one count per minute. This is because when the disk is in idle mode, the counter stops advancing. This is only supposed to happen in standby mode. This will be corrected in Maxtor product lines released after October 2004."

From CDI's FAQ:

"Strange "Power on Hours"

A part of Maxtor HDD could count only 65535 minuites (about 1092 hours)."

I wonder if different manufacturers now have different ideas about how to record that value? Or maybe there are just lots more bugs in this implementation.

 

[Elixer]

Does CrystalDiskInfo get its data from S.M.A.R.T.? If so, then it is no more accurate than the source.

Indeed it does.
Sometimes OEMs like to tweak their settings, and it takes some time for the author to either get a drive, or get the new white papers describing what was changed to fix it. Then again, it might just be a simple bug.