Re: Hard Drives..(MTBF) of 2 million hours. They are supported by a five-year limited warranty.

Discussion in 'NZ Computing' started by Gordon, Feb 5, 2011.

  1. Gordon

    Gordon Guest

    On 2011-02-04, Suzie Wong <> wrote:
    >
    > .Hitachi GST has today announced its new Ultrastar 7K3000
    > enterprise-class hard drives, which are designed for use with 24x7
    > applications in data centres. The new 3.5in drives feature a capacity of
    > up to 3TB and are claimed by Hitachi to be the "world's first and only"
    > 7200rpm hard drives with a mean time between failure (MTBF) of 2 million
    > hours. They are supported by a five-year limited warranty.
    >

    Right folks tlets consider just how long 2 millions hours is.

    There are 8760 hours in a year, so its 228.3 years. It will take longer than
    that to prove the claim. So is worth anything? A best guess maybe
     
    Gordon, Feb 5, 2011
    #1
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  2. Gordon

    Murray Symon Guest

    Gordon wrote:

    > On 2011-02-04, Suzie Wong <> wrote:
    >>
    >> .Hitachi GST has today announced its new Ultrastar 7K3000
    >> enterprise-class hard drives, which are designed for use with 24x7
    >> applications in data centres. The new 3.5in drives feature a capacity of
    >> up to 3TB and are claimed by Hitachi to be the "world's first and only"
    >> 7200rpm hard drives with a mean time between failure (MTBF) of 2 million
    >> hours. They are supported by a five-year limited warranty.
    >>

    > Right folks tlets consider just how long 2 millions hours is.
    >
    > There are 8760 hours in a year, so its 228.3 years. It will take longer
    > than that to prove the claim. So is worth anything? A best guess maybe


    No, that would only be the case if it was "TBF" (Time Between Failures).
    The "M" stands for "mean", because it is a theoretical statistical
    measure over a very large number of units. It dosen't mean much for
    one sample item.
     
    Murray Symon, Feb 5, 2011
    #2
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  3. Gordon

    Roger_Nickel Guest

    Re: Hard Drives..(MTBF) of 2 million hours. They are supported by afive-year limited warranty.

    On Sat, 05 Feb 2011 19:44:49 +1300, Murray Symon wrote:

    > Gordon wrote:
    >
    >> On 2011-02-04, Suzie Wong <> wrote:
    >>>
    >>> .Hitachi GST has today announced its new Ultrastar 7K3000
    >>> enterprise-class hard drives, which are designed for use with 24x7
    >>> applications in data centres. The new 3.5in drives feature a capacity
    >>> of up to 3TB and are claimed by Hitachi to be the "world's first and
    >>> only" 7200rpm hard drives with a mean time between failure (MTBF) of 2
    >>> million hours. They are supported by a five-year limited warranty.
    >>>

    >> Right folks tlets consider just how long 2 millions hours is.
    >>
    >> There are 8760 hours in a year, so its 228.3 years. It will take longer
    >> than that to prove the claim. So is worth anything? A best guess maybe

    >
    > No, that would only be the case if it was "TBF" (Time Between Failures).
    > The "M" stands for "mean", because it is a theoretical statistical
    > measure over a very large number of units. It dosen't mean much for one
    > sample item.


    And it doesn't relate to the real world of thunderstorms, fan failures,
    power surges, mechanical shock---to name only a few of the more obvious
    possible problems. Also--MTBF is measured on new devices, it says nothing
    about the way devices age, refer to the other thread on capacitor
    failures.
     
    Roger_Nickel, Feb 5, 2011
    #3
  4. On 6 Feb 2011 09:27:57 +1300, Roger_Nickel <> wrote:

    >On Sat, 05 Feb 2011 19:44:49 +1300, Murray Symon wrote:
    >
    >> Gordon wrote:
    >>
    >>> On 2011-02-04, Suzie Wong <> wrote:
    >>>>
    >>>> .Hitachi GST has today announced its new Ultrastar 7K3000
    >>>> enterprise-class hard drives, which are designed for use with 24x7
    >>>> applications in data centres. The new 3.5in drives feature a capacity
    >>>> of up to 3TB and are claimed by Hitachi to be the "world's first and
    >>>> only" 7200rpm hard drives with a mean time between failure (MTBF) of 2
    >>>> million hours. They are supported by a five-year limited warranty.
    >>>>
    >>> Right folks tlets consider just how long 2 millions hours is.
    >>>
    >>> There are 8760 hours in a year, so its 228.3 years. It will take longer
    >>> than that to prove the claim. So is worth anything? A best guess maybe

    >>
    >> No, that would only be the case if it was "TBF" (Time Between Failures).
    >> The "M" stands for "mean", because it is a theoretical statistical
    >> measure over a very large number of units. It dosen't mean much for one
    >> sample item.

    >
    >And it doesn't relate to the real world of thunderstorms, fan failures,
    >power surges, mechanical shock---to name only a few of the more obvious
    >possible problems. Also--MTBF is measured on new devices, it says nothing
    >about the way devices age, refer to the other thread on capacitor
    >failures.




    You know F all about MTBF, I do and have been involved in its
    Calculations..
     
    William Brown, Feb 5, 2011
    #4
  5. Gordon

    Boots Guest

    Re: Hard Drives..(MTBF) of 2 million hours. They are supported by afive-year limited warranty.

    On Sun, 06 Feb 2011 11:28:21 +1300, William Brown wrote:

    > You know F all about MTBF, I do and have been involved in its
    > Calculations..


    Now this *is* interesting. Woger is involved in calculating the mean time
    before failure for hard disc drives manufactured by Hitachi. I suppose
    that is why Hitachi has published a MTBF of 228.3 years!

    Nobody else on the planet could have devised such a clearly erroneous
    statistic!


    --
    "Filtering the Internet is like trying to boil the ocean"
     
    Boots, Feb 5, 2011
    #5
  6. Gordon

    Richard Guest

    Re: Hard Drives..(MTBF) of 2 million hours. They are supported bya five-year limited warranty.

    On 6/02/2011 11:57 a.m., Boots wrote:
    > On Sun, 06 Feb 2011 11:28:21 +1300, William Brown wrote:
    >
    >> You know F all about MTBF, I do and have been involved in its
    >> Calculations..

    >
    > Now this *is* interesting. Woger is involved in calculating the mean time
    > before failure for hard disc drives manufactured by Hitachi. I suppose
    > that is why Hitachi has published a MTBF of 228.3 years!
    >
    > Nobody else on the planet could have devised such a clearly erroneous
    > statistic!


    Would be interesting to see if a business running 228 of the drives only
    has one failure per year of them. I think the results will not back up
    the million hour claims.
     
    Richard, Feb 6, 2011
    #6
  7. Gordon

    Roger_Nickel Guest

    Re: Hard Drives..(MTBF) of 2 million hours. They are supported by afive-year limited warranty.

    On Sun, 06 Feb 2011 11:28:21 +1300, William Brown wrote:

    > On 6 Feb 2011 09:27:57 +1300, Roger_Nickel <> wrote:
    >
    >>On Sat, 05 Feb 2011 19:44:49 +1300, Murray Symon wrote:
    >>
    >>> Gordon wrote:
    >>>
    >>>> On 2011-02-04, Suzie Wong <> wrote:
    >>>>>
    >>>>> .Hitachi GST has today announced its new Ultrastar 7K3000
    >>>>> enterprise-class hard drives, which are designed for use with 24x7
    >>>>> applications in data centres. The new 3.5in drives feature a
    >>>>> capacity of up to 3TB and are claimed by Hitachi to be the "world's
    >>>>> first and only" 7200rpm hard drives with a mean time between failure
    >>>>> (MTBF) of 2 million hours. They are supported by a five-year limited
    >>>>> warranty.
    >>>>>
    >>>> Right folks tlets consider just how long 2 millions hours is.
    >>>>
    >>>> There are 8760 hours in a year, so its 228.3 years. It will take
    >>>> longer than that to prove the claim. So is worth anything? A best
    >>>> guess maybe
    >>>
    >>> No, that would only be the case if it was "TBF" (Time Between
    >>> Failures). The "M" stands for "mean", because it is a theoretical
    >>> statistical measure over a very large number of units. It dosen't
    >>> mean much for one sample item.

    >>
    >>And it doesn't relate to the real world of thunderstorms, fan failures,
    >>power surges, mechanical shock---to name only a few of the more obvious
    >>possible problems. Also--MTBF is measured on new devices, it says
    >>nothing about the way devices age, refer to the other thread on
    >>capacitor failures.

    >
    >
    >
    > You know F all about MTBF, I do and have been involved in its
    > Calculations..


    OK I'll bite. MTBF calculations assume that the component parts have a
    consistent failure rate with age and that parts fail independently of
    each other. In fact the component failure rate has a bathtub shaped
    curve. First the early failures then a low failure rate during the
    service life and then an increasing failure rate due to component aging
    (dopant migration, lead bond failures, encapsulation failures etc.). MTBF
    is nothing more than a useful measuring stick.

    The idea that you could build a storage array out of a few hundred of
    these drives and run it for 223 years before half of the drives fail is
    patently and obviously absurd. You would know this if you read a few
    manufacturers' data sheets--the methods used for MTBF calculation are not
    a secret.

    For instance (from an old National Semiconductor datasheet) :-
    "...Mean time between failures (MTBF) is the mean (average) time between
    failures of a system, the reciprocal of the failure rate in the special
    case when the failure rate is constant..."

    I guess that you didn't work for NatSemi...
     
    Roger_Nickel, Feb 6, 2011
    #7
  8. Gordon

    Boots Guest

    Re: Hard Drives..(MTBF) of 2 million hours. They are supported by afive-year limited warranty.

    On Sun, 06 Feb 2011 13:34:41 +1300, Richard wrote:

    > Would be interesting to see if a business running 228 of the drives only
    > has one failure per year of them.


    One failure a year for every 228 manufactured |= a mean time before
    failure of 228 years.


    --
    "Filtering the Internet is like trying to boil the ocean"
     
    Boots, Feb 6, 2011
    #8
  9. Gordon

    Richard Guest

    Re: Hard Drives..(MTBF) of 2 million hours. They are supported bya five-year limited warranty.

    On 6/02/2011 4:24 p.m., Boots wrote:
    > On Sun, 06 Feb 2011 13:34:41 +1300, Richard wrote:
    >
    >> Would be interesting to see if a business running 228 of the drives only
    >> has one failure per year of them.

    >
    > One failure a year for every 228 manufactured |= a mean time before
    > failure of 228 years.


    Assuming you really meant !=, then please explain what it does mean? I
    have been told that is exactly what it means.
     
    Richard, Feb 6, 2011
    #9
  10. Gordon

    Boots Guest

    Re: Hard Drives..(MTBF) of 2 million hours. They are supported by afive-year limited warranty.

    On Mon, 07 Feb 2011 10:03:27 +1300, Richard wrote:

    >> One failure a year for every 228 manufactured |= a mean time before
    >> failure of 228 years.

    >
    > Assuming you really meant !=, then please explain what it does mean? I
    > have been told that is exactly what it means.


    Put it this way, have you EVER had ANY HDD last longer *in continuous
    active service* (ie constantly spinning and regularly writing and/or
    reading data) than 20 years? Let alone 228 years!

    Case in point, the manufacturer only offers a "limited warranty" of a
    mere 5 years in comparison to the length of time they claim 50% of those
    HDDs will last for.


    --
    "Filtering the Internet is like trying to boil the ocean"
     
    Boots, Feb 7, 2011
    #10
  11. Gordon

    dtcorbett

    Joined:
    Mar 8, 2012
    Messages:
    1
    FWIW I have been running 84 of these for the last year with 0 failures. We are buying more. I have 144GB FC drives with one failure almost weekly, but we are running about 600 of them. Do not try this at home. Clear anecdotal evidence that at the very least confirms that these drives are more reliable than their predicessors.
     
    dtcorbett, Mar 8, 2012
    #11
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