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Author Topic: Hard Drive SMART Stats - from the BackBlaze Blog  (Read 2560 times)

4wd

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Hard Drive SMART Stats - from the BackBlaze Blog
« on: November 19, 2014, 06:28:55 PM »
Hard Drive SMART Stats

Quote
I’ve shared a lot of Backblaze data about hard drive failure statistics While our system handles a drive failing, we prefer to predict drive failures, and use the hard drives’ built-in SMART metrics to help. The dirty industry secret? SMART stats are inconsistent from hard drive to hard drive.

With nearly 40,000 hard drives and over 100,000,000 GB of data stored for customers, we have a lot of hard-won experience. See which 5 of the SMART stats are good predictors of drive failure below. And see the data we have started to analyze from all of the SMART stats to see which other ones predict failure.

Quote
From experience, we have found the following 5 SMART metrics indicate impending disk drive failure:

    SMART 5 – Reallocated_Sector_Count.
    SMART 187 – Reported_Uncorrectable_Errors.
    SMART 188 – Command_Timeout.
    SMART 197 – Current_Pending_Sector_Count.
    SMART 198 – Offline_Uncorrectable.
« Last Edit: November 19, 2014, 08:46:49 PM by 4wd »

ewemoa

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Re: Hard Drive SMART Stats - from the BackBlaze Blog
« Reply #1 on: November 19, 2014, 10:26:57 PM »
Thanks for updating the post with the metrics they pay attention to.

IainB

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Re: Hard Drive SMART Stats - from the BackBlaze Blog
« Reply #2 on: November 20, 2014, 06:48:44 AM »
Interesting. Based on sound observations. That tallies pretty closely with what HDS (Hard Disk Sentinel) was reporting about the deteriorating state of my laptop hard drive a while back. I shall make a note of those for future reference.
This was a Seagate ST9500420AS 2½" laptop drive:

HDS Seagate ST9500420AS - failing HP ENVY laptop hard disk.png
« Last Edit: November 20, 2014, 07:22:47 AM by IainB, Reason: Added image. »

4wd

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Re: Hard Drive SMART Stats - from the BackBlaze Blog
« Reply #3 on: November 20, 2014, 08:02:36 PM »
^Those stats indicate that it's still a good working HDD AFAIAC  :)

Remember this one:

2012-02-03_16-18-18.jpgHard Drive SMART Stats - from the BackBlaze Blog

Almost three years later:

2014-11-21 12_55_41.pngHard Drive SMART Stats - from the BackBlaze Blog

SeraphimLabs

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Re: Hard Drive SMART Stats - from the BackBlaze Blog
« Reply #4 on: November 20, 2014, 09:54:38 PM »
Because the drive had not run out of spare sectors, and was able to remap 100% of them to spare areas.

I've salvaged quite a few 'bad' devices that way, simply overwriting them repeatedly a few times to brute force trigger the remapping sequence.

IainB

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Re: Hard Drive SMART Stats - from the BackBlaze Blog
« Reply #5 on: November 21, 2014, 05:03:34 AM »
@4wd: Blimey. What did you do to get that result? Why does it have the Plus and Minus next to the 100% Health report? I've never seen that before.
Did you somehow set the offset to -1639, or did HDS do that? I haven't thrown away that "bad" drive of mine. If it still has life and is not deteriorating, then maybe I should put a new image on it?

Is that (writing a new image) the sort of thing @SeraphimLabs means where he writes:
...I've salvaged quite a few 'bad' devices that way, simply overwriting them repeatedly a few times to brute force trigger the remapping sequence.
??
Overwriting them repeatedly is what Spinrite does, I think - except it didn't work on that particular drive of mine:
...The software was unable to run on my hardware (disk drive) - for the simple technical reason that it was not possible to effect a BIOS switch change to enable it. ...

4wd

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Re: Hard Drive SMART Stats - from the BackBlaze Blog
« Reply #6 on: November 21, 2014, 05:26:11 AM »
@4wd: Blimey. What did you do to get that result? Why does it have the Plus and Minus next to the 100% Health report? I've never seen that before.
Did you somehow set the offset to -1639, or did HDS do that?

The +/- appears when you put in an offset - which you can do next to any of the S.M.A.R.T. values.

That drive is over 5 years old and still spinning its wheels.

You can run a Low Level Format a couple of times to see if the sectors get remapped, (what I usually do when a HDD starts getting flakey), or use something like MHDD.  Fill up the HDD with big files a few times, at some point it may trigger the remap if the sector gets hit enough times and produces errors.