Sd Card size???


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  1. RedVr4

    RedVr4 New Member This Topic's Starter

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    Noob here. I just upgraded my sd card from the stock 2 Gb to an 8 Gb.
    Looking at the size from the pc the size reported is correct, just under 8 Gb formatted FAT32. When I look at the a Total Space in the phone it reports just over 7.5 Mb.

    Anybody know what I did wrong.
    I did copy the contents of the old card to the pc first, there were no partitions and then copied the data to the new card but the size is being reported incorrectly.

    Bill
     

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  2. Xyro

    Xyro 4 8 15 16 23 42 Moderator

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    Is this bit supposed to read GB?

    Because that's normal. The advertised size of memory is always larger than the actual size. Computers think of one GB as 1024MB, one MB as 1024KB and so on, whilst the box will give the size as if 1GB = 1000MB and so on, meaning they seem bigger. It's a bit of a scam really.

    (I can't remember exactly why computers treat numbers like this, but it's all to do with binary (base 2 maths) and how they like to use double numbers. Start with the no. 1 and keep doubling and you'll see all the numbers you associate with computers, 16, 32, 256, 1024 and so on).
     
  3. RedVr4

    RedVr4 New Member This Topic's Starter

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    I am a noob to the HTC Hero not what the difference between a Gb and an Mb is.

    Yes it should be Gb. Has anyone else seen this?

    Bill
     
  4. rizzla

    rizzla Well-Known Member

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    easy way to remember

    1000k = 1 mb

    1000 mb = 1 gb

    1000 gb = 1 terabyte

    Also the system will use some of the space straight away so if you have 8 gb some of it will be used up by the system the moment its formatted.
     
  5. Xyro

    Xyro 4 8 15 16 23 42 Moderator

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    That's exactly what my 8GB card says.
     
  6. daveybaby

    daveybaby Well-Known Member

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    While this is true for hard disks (the ones with rotatey bits inside them), it's not true for solid state disks (SSDs) or SD cards.

    If you bought an 8GB hard disk, it would probably have 8,000,000,000 bytes of storage, since HDD manufacturers (and customers that arent programmers) tend to use 1KB = 1000 bytes, 1MB = 1000 KB etc. This might actually get reported as 7.5GB by a computer because the computer is using 1KB = 1024 bytes etc (so it thinks of 8GB as having 8,589,934,592 bytes of storage).

    BUT: if you buy an 8GB SSD or SD card, it will actually have 8,589,934,592 bytes of storage. This is because solid state devices use 1KB = 1024 bytes - the same as computer memory.

    Formatting any storage device uses up some of the raw unformatted storage capacity, but this shouldnt be anywhere near the 0.5GB that appears to be missing in this case. hmmm... puzzling.
     
  7. jev

    jev Well-Known Member

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    @daveybaby: no, it's not. Today's SDHC cards implement 1 GB as 10^9 bytes, not 2^30.

    The numbers below are reported by the cards themselves in a response to a CMD9 (get CSD) message as per SD Card Association's 'Simplified Physical Layer Specification Version 2.00'.

    The first one I tested was a Kingston 8 GByte card that reports 16014336 blocks, each 512 bytes per block makes a grand total of 8,199,340,032 bytes or roughly 7.63 GByte.

    Another (unbranded) 8GB card reports 15526912 blocks in its CSD, 7,949778,944 bytes in total or 7.4 GByte.

    I do not have a Sandisk 8 GByte card here, but I do have a Sandisk 4 GByte card. That card reports 7743488 blocks of 512 bytes each or just under 3.7 GByte.
     
  8. daveybaby

    daveybaby Well-Known Member

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    You learn something new every day. Nice one.
     
  9. jev

    jev Well-Known Member

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    It's easy to explain, Dave: most probably, there's hardware for the full 8 GByte but some of it might be mapped out for use by the embedded microcontroller on the card itself - it is an embedded system after all. What is not used by the uC can than be made available to the user-side of the card.
     
  10. amnesia

    amnesia Well-Known Member

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    My new transcend 8Gb class 6 SDHC card for my DSLR is 7.69Gb available once formatted as FAT32.

    Sounds about right to me.

    To the OP - anything around 7.5GB is correct for a fomatted 8Gb card.
     

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