"Low-level" format in Canon A590 - what does it do?

Discussion in 'Canon' started by Peabody, Feb 27, 2010.

  1. Peabody

    Peabody Guest

    Does anyone happen to know what exactly happens in the "low-level"
    format of an SD card in a Canon P&S? What I'm specifically trying
    to find out is whether it erases the card before intializing the
    file system. In flash memory, erasing is not just overwriting, but
    actually returning the memory to its unprogrammed state, like what
    we used to do with UV light applied to an EPROM.

    I'm trying to get the maximum video write speed for another
    application, and in theory an erased card will write faster. I
    can't find any other way to erase a card, so I thought maybe the
    Canon would do it.
     
    Peabody, Feb 27, 2010
    #1
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  2. My first suggestion is to try it and see what happens. I will not hurt
    the card. I've heard that it's not a good idea to format a card outside
    of the camera so do it in the camera for safety. I don't think that it
    will make much difference but it can't hurt to try. If you really want
    to do this right get a card with 6 speed rating. In the case of video
    the sustained wright speed is more important than the much more
    advertised burst rate. You can find this rating on the SD card unclosed
    in braces like this (6). a much slower 2 or 4 speed are much more common.

    John Passaneau
     
    John Passaneau, Feb 27, 2010
    #2
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  3. Peabody

    Ray Fischer Guest

    How long does it take?

    Completely erasing a 2GB memory card should take a minute or two.
    Writing a new file system will take a couple of seconds.
    Nobody does that. It's probably not possible.
    You'd do better to get a faster memory card and stop wasting time on
    chasing a mythical 1% speed increase.
     
    Ray Fischer, Feb 27, 2010
    #3
  4. Peabody

    ray Guest

    I can't speak to that particular camera, but I can tell you a few
    generalities gathered from 30 years as a computer professional:

    1) it is probably best to format a card in the camera you intend to use
    it on. Reason: some cameras have an incomplete implementation of the
    filesystem structure (due to the fact that they contain very limited
    processing power). That is the main reason that they sometimes become
    corrupted after a bit of saving and deleting images. That problem is not
    as bad as it used to be, but . . .

    2) you should be able to do a low level format in a card reader attached
    to a computer. If you did that, I'd still recommend doing a 'quick
    format' on the camera it will be used with. Fact is, they are not using
    any novel filesystem on the cards - they are still a variant of MS
    filesystems - so most computers should understand that.

    3) the main advantage of a 'low level' format on a memory card would be
    that the data is erased - overwritten. A 'quick format' simply resets the
    file allocation table - removing the directory contents. Until some data
    is overwritten, the previous data can still be retrieved with varying
    degrees of success.

    I'd be surprised if the access was measurably faster on a low level
    formatted card than one that had a quick format done. To my knowledge, it
    does not make in difference in write time depending on what was there
    before, but I could be wrong on that point.
     
    ray, Feb 27, 2010
    #4
  5. Peabody

    Ted Banks Guest

    For the speed issue:

    If it's an SD card and not an SDHC card (4GB or less only, though some 4GB
    cards are also SDHC) format it in FAT16. It can improve the write speed up
    to 30% in Canon P&S cameras. Don't use the camera, use your computer and a
    card-reader for this. Formatting in the camera will format it as FAT32.

    After using it for a while for many files and file deletions and it seems
    to slow down, you can retain that speed by using Windows tools to
    defragment it. It will speed up as if freshly formatted in FAT16 again
    without a reformat needed. Most other stand-alone defragment utilities
    don't seem to recognize SD cards in a card reader. Contrary to most of the
    opinions you'll read online by those who post what they don't really know,
    defragmenting does work as well as a fresh format. Defragment twice, as one
    time doesn't seem to catch all of the gaps the first time.
     
    Ted Banks, Feb 27, 2010
    #5
  6. Peabody

    Ted Banks Guest

    Contrary to that opinion, class ratings for cards are for read-speed only.
    The write speed can be as low as 50% of that, so using tricks like
    formatting in FAT16 can be more beneficial for write-speed than just buying
    a faster card and wasting your money for no appreciable write-speed gain.
     
    Ted Banks, Feb 27, 2010
    #6
  7. Simply reformat it once in camera. Done.
     
    John McWilliams, Feb 28, 2010
    #7
  8. Peabody

    LOL! Guest

    You're a moron.
     
    LOL!, Feb 28, 2010
    #8

  9. Right, "Ted".... always take the more convoluted path.
     
    John McWilliams, Feb 28, 2010
    #9
  10. Peabody

    LOL! Guest

    http://chdk.wikia.com/wiki/Benchmarks

    You're a moron.

    You weren't just happy with being told that you are a moron, you insisted
    that I prove you are a moron to the whole world.

    Better to remain silent and be thought a fool than to open your mouth again
    and remove all doubt again.


    LOL!
     
    LOL!, Feb 28, 2010
    #10
  11. Peabody

    dwight Guest

    It's a good question, and one that I've wondered about, myself. My S3 has
    the low level format option, but the manual only has this to say:

    "You should select the [Low Level Format] option if you suspect the
    read/write speed of a memory card has dropped. A low level format may
    require 2 to 3 minutes with some memory cards."

    Not big on specifics.

    dwight
     
    dwight, Feb 28, 2010
    #11
  12. Yes, lol, Ted, and a dozen other nyms per month, words which may haunt......
     
    John McWilliams, Feb 28, 2010
    #12
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