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  1. #1
    FLAC Trooper ArcticFox's Avatar
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    Real and advertised hard drive sizes - why you don't get all the space you pay for.

    I see a lot of threads asking why someone's new 80GB drive only shows up as 74.5GB, etc, and why a newly purchased 250GB drive only shows up in Windows as 137GB. Thanks to duffyone, I present the following, pulled from Western Digital's website:

    Decimal vs. Binary:
    For simplicity and consistency, hard drive manufacturers define a megabyte as 1,000,000 bytes and a gigabyte as 1,000,000,000 bytes. This is a decimal (base 10) measurement and is the industry standard. However, certain system BIOSs, FDISK and Windows define a megabyte as 1,048,576 bytes and a gigabyte as 1,073,741,824 bytes. Mac systems also use these values. These are binary (base 2) measurements.

    To Determine Decimal Capacity:
    A decimal capacity is determined by dividing the total number of bytes, by the number of bytes per gigabyte (1,000,000,000 using base 10).

    To Determine Binary Capacity:
    A binary capacity is determined by dividing the total number of bytes, by the number of bytes per gigabyte (1,073,741,824 using base 2).
    This is why different utilities will report different capacities for the same drive. The number of bytes is the same, but a different number of bytes is used to make a megabyte and a gigabyte. This is similar to the difference between 0 degrees Celsius and 32 degrees Fahrenheit. It is the same temperature, but will be reported differently depending on the scale you are using.


    --------------------------------------------------------------------------------


    Various Drive Sizes and their Binary and Decimal Capacities


    Drive Size in GB Approximate Total Bytes Decimal Capacity
    (bytes/1,000,000,000)
    Approximate Binary Capacity (bytes/1,073,724,841)
    10 GB 10,000,000,000 10 GB 9.31 GB
    20 GB 20,000,000,000 20 GB 18.63 GB
    30 GB 30,000,000,000 30 GB 27.94 GB
    36 GB 36,000,000,000 36 GB 33.53 GB
    40 GB 40,000,000,000 40 GB 37.25 GB
    60 GB 60,000,000,000 60 GB 55.88 GB
    74 GB 74,000,000,000 74 GB 68.91 GB
    80 GB 80,000,000,000 80 GB 74.51 GB
    100 GB 100,000,000,000 100 GB 93.13 GB
    120 GB 120,000,000,000 120 GB 111.76 GB
    160 GB 160,000,000,000 160 GB 149.01 GB
    180 GB 180,000,000,000 180 GB 167.64 GB
    200 GB 200,000,000,000 200 GB 186.26 GB
    250 GB 250,000,000,000 250 GB 232.83 GB
    300 GB 300,000,000,000 300 GB 279.40 GB
    320 GB 320,000,000,000 320 GB 298.02 GB
    Now, for those running into the 137GB limit, or any other size limit for that matter, you either...
    A) Don't have Service Pack 1 installed (assuming you run XP)
    or
    B) Your drive controller is old enough where it doesn't support large drives. I ran into this problem with an old eMachines that had a 466Mhz Celeron. I bought an 80GB ATA/133 Maxtor and then realized my board didn't support something "that large". I could have bought a PCI IDE controller however, but decided to build a new system instead.

    I'd like for this to be a sticky, any mods up for it?
    Also, if I made a mistake, or you would like to add to it, speak up!

  2. #2
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    GB = decimal SI unit, 1,000,000,000 bytes
    GiB = binary SI unit, 1,073,741,824 bytes

    Nothing wrong with the advertized drive sizes - mucho wrong with all software that displays GiB and writes a "GB" suffix behind it.

    On the other side of the story, I've yet to hear someone complain they bought a "1 GB" memory DIMM and got 1,074 GB ...

  3. #3
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    "When a Byte is not a Byte" is an article that goes into further explaination of how to read
    actual drive sizes found at: http://compreviews.about.com/od/stor...ualHDSizes.htm

  4. #4
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    That article, like so many others, has the units of measurement wrong. See my previous post.

    SI units are internationally standardized.

  5. #5
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    That's where you have to correct the article's author. But for all too many users the simple
    terms generally suffice without question. Different units of measurement obviously reflect a
    totally different result when using the same multiplier.

  6. #6
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    The point - and the "simple term" you're asking for is:

    ADVERTIZED harddisk sizes are CORRECT.

    ... because "GB" is the decimal unit. Buyers of an "80 GB" drive may expect to get 80,000,000,000 bytes.

    The linked article misses the point entirely, no point in trying to correct it. So does the section quoted from WD in this thread's first post.

    Linux btw gets the GB vs. GiB thing right. Most other software, including BIOSes, OSes and utilities, doesn't.

    So don't rant at the harddisk manufacturers, rather look to it that the software is being corrected to put the right units to the numbers.

  7. #7
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    Actually the "simple" layman's terms can be read at: http://en.wikipedia.org/wiki/Gigabytes

  8. #8
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    ... which is just a more verbose version of what I said above. Thanks for proving my point.

  9. #9
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    Glad to be of help!

  10. #10
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    very good thread. this should let people know why their drives show less space than advertised. i hate it when people complain and say something like "i bought this huge 200GB drive and i only get 186GB, whats wrong?"

    for those of you getting 137GB for a drive that is much larger, its most probably because your motherboard doesnt support it, or your OS doesnt support it.

  11. #11
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    Once again:

    DRIVES DO NOT HAVE LESS CAPACITY THAN ADVERTIZED.

    Drive advertizing uses the abbreviation "GB", which denotes THE DECIMAL UNIT. So you can expect your "200GB" drive to have 200,000,000,000 bytes, no more.

    As pointed out above already, the wrongness is in fact on the other end - 200 GB are about 186 GiB. If your software shows that as "186GB", then the software is bull not the drive advertizing.
    Last edited by Peter M; August 12th, 2006 at 06:20 AM.

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    oh i see.... so the real way to write "gigabyte" is GiB

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    I would like to point out a few things I have learned over the years. First, the only place in any part of the computer industry a MB is 1,000k is hard drive makers. No other part of the computer world sees it that way.

    Some of you who have been around will remember this, back in days when computers were first being made to actually be for home use, whole programs fit on a 5 1/4 floppy that held 360k of data max. When very small hard drives, by todays standards, were costing much more then massive hard drives cost today, the difference of even a 1/4 MB was a major difference.

    So at some point, one of the drive makes decided to use the 1,000k to inflate the space of there drives to give them selfs an edge on the market. It was a simple marketing ploy. And of course, all the others followed to even the playing field.

    The 1,024k = MB standard was defined way back in the 50's when the very first punch card computers were built. Before there was really such a thing as a hard drive as we know it today. In fact I remember my dad having a true 10 MB hard drive. And the famous last words, "I will never fill that much space up". We never let him forget that.

    It is the same concept as when AMD actually started to make there CPU's that could keep up with Intel's. At that time, Intel was losing too much of the market too fast. So Intel's quick answer was to lessen the amount of data processed within a clock cycle. And because the number of clock cycles per second is what the speed rating of a CPU is based off of, Intel showed much higher click speeds then AMD, which is why the use the + rating on there CPU's.

    Which explained why a 2 gig'ish AMD 3000+ would benchmark around the same as an Intel 2.8-2.9 gig CPU. Regardless of the number of clock cycles per second, the actually amount of data processed per second was close to the same.

    Enjoy~

  14. #14
    Member ru1di's Avatar
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    Thank you nevtime - that explained everything.
    No timeouts, no substitues, no halftimes, running is a sport, not a game."

  15. #15
    Ultimate Member elroy's Avatar
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    I sold off a pair of used Maxtor 160gb drives and bought a pair of new Seagate 160gb drives. Mostly for the longer warranty. After installation and formatting I found out each Seagate was about 4gb smaller formatted.

    I wasn't to happy.
    “Those who desire to give up freedom in order to gain security will not have, nor do they deserve, either one.”
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    hey thanks for those facts! very interesting read

  17. #17
    Ultimate Member elroy's Avatar
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    Quote Originally Posted by nevtime View Post
    It is the same concept as when AMD actually started to make there CPU's that could keep up with Intel's. At that time, Intel was losing too much of the market too fast. So Intel's quick answer was to lessen the amount of data processed within a clock cycle. And because the number of clock cycles per second is what the speed rating of a CPU is based off of, Intel showed much higher click speeds then AMD, which is why the use the + rating on there CPU's.
    IBM/Cyrix started the "+" cpu ratings. They started putting out chips with a larger cache that were able to perform nearly the same as faster Intel Pentium chips. Some examples: Cyrix 300 actually ran at 233mhz. The Cyrix 366 actually ran at 300mhz. Their 166 ran at 133mhz. They did this as far back as the 100 or 120 mhz chips but I don't remember the exact speed differences.

    This was the first processor company to utilize an "oversized" cache to greatly enhance performance. Now Cyrix is totally forgotten and AMD and Intel are playing the "my cache is bigger than yours game".

    Regarding actual drive size. When installing a drive over 120gb you should review this link. http://support.microsoft.com/kb/305098
    If your registry doesn't have this entry the day your data crosses the 128gb or 137gb line you may have BIG problems. The service packs are supposed to address this issue and install the correct registry entry but it doesn't always work. There is a little .reg file available on the web that will make this entry for you. Run a search for it.
    Last edited by elroy; April 13th, 2007 at 10:45 AM.
    “Those who desire to give up freedom in order to gain security will not have, nor do they deserve, either one.”
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    thanks... i DEF dont want to run into that problem

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    Exclamation Get real

    Peter M:

    What hard drive manufacturer do you work for? Do you know the history of this IS & how this measure was established?

    Lets see. Let's blame everyone else, OSs, utilities, other software, computers, processors, flashcards, etc, because they are reporting a binary number as a GB, MB, etc, a convention that predates this particular IS. Which label makes sense technically for computers and how they work?

    And which # works better to inflate capacity as a sales tool. Who benefits from the confusion? Who is creating the confusion? It is the only reason hard drive manufacturers have for not following the historic norm for this measurement in computer technology.

    But you do "win" on a technicality! If you post it enough times here, others might even believe in your "rightness" over those stupid enough around computers to not be aware that HD manufacturers are using a different scale.

    Dave

  20. #20
    THE Gimp Clown Fish! nemowolf's Avatar
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    Quote Originally Posted by ghoste View Post
    Peter M:

    What hard drive manufacturer do you work for? Do you know the history of this IS & how this measure was established?

    Lets see. Let's blame everyone else, OSs, utilities, other software, computers, processors, flashcards, etc, because they are reporting a binary number as a GB, MB, etc, a convention that predates this particular IS. Which label makes sense technically for computers and how they work?

    And which # works better to inflate capacity as a sales tool. Who benefits from the confusion? Who is creating the confusion? It is the only reason hard drive manufacturers have for not following the historic norm for this measurement in computer technology.

    But you do "win" on a technicality! If you post it enough times here, others might even believe in your "rightness" over those stupid enough around computers to not be aware that HD manufacturers are using a different scale.

    Dave
    Welcome to TechIMO but i think your beating on a year old horse my friend...

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