Is my card is really class 4 (have benchmark screenshot)

Discussion in 'GBA - Flashing Hardware and Software' started by tomrev, Oct 30, 2009.

  1. tomrev
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    Member tomrev GBAtemp Fan

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    I have bought 4 GB micro SD for my DS flash card. Form pic. below, It show the benchmark of my MicroSD card. I'm not sure it's really class 4 because some write speed result is below 4000 KB/s. Did I misunderstand?

    [​IMG]
     
  2. gtmtnbiker

    Member gtmtnbiker GBAtemp Regular

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    What brand of flash card did you get and where did you buy it from?
     
  3. tomrev
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    Member tomrev GBAtemp Fan

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    Kingston 4GB class 4. I bought from local shop.
     
  4. gtmtnbiker

    Member gtmtnbiker GBAtemp Regular

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    Ok, chances are it's a legit SD card. The 4MB/s is the maximum theoretical transfer rate for a class 4 card. The fact that you're around that number seems to confirm that you do have a class 4 card.
     
  5. tomrev
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    Member tomrev GBAtemp Fan

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    It's may not correct to use the maximum transfer rate to classify class of Micro SD.
    I have read on wikipedia at http://en.wikipedia.org/wiki/Secure_Digital


    ****************************
    SD Speed Class Ratings

    SD Cards and SDHC Cards have Speed Class Ratings defined by the SD Association. The SD Speed Class Ratings specify the following minimum write speeds based on "the best fragmented state where no memory unit is occupied":[8]

    * Class 2: 2 MByte/s - 13x
    * Class 4: 4 MByte/s - 26x
    * Class 6: 6 MByte/s - 40x
    ****************************



    *** minimum write speeds based on "the best fragmented state where no memory unit is occupied" ***

    What is sentence "the best fragmented state where no memory unit is occupied" mean? And, Does my benchmark result can determine the class?
     
  6. gtmtnbiker

    Member gtmtnbiker GBAtemp Regular

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    I stand corrected. Yes, the class rating pertains to the minimum, not maximum write transfer rates. There's a good thread over here where they discuss SD class ratings.

    Apparently your benchmark is not necessarily valid. The SD governing body apparently has their own benchmark used to determine the class rating. Regarding fragmentation, you want to have no fragmentation. The more the disk is fragmented, the slower your write/read speeds will be.
     
  7. tomrev
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    Member tomrev GBAtemp Fan

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    After I read your link, I get many useful info about Micro SD(HC)'s class. I think my card is possible true / false class 4. Class specification is loose that manufacture can adjust measurement as they wish. Thank you gtmtnbiker.
     

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