AGFA SD card - Palmtop

This is a discussion on AGFA SD card - Palmtop ; drocillo wrote: > Michael J. Mahon wrote: > >>drocillo wrote: >> >>>Michael J. Mahon wrote: >>> >>> >>> >>>>I think the problem is that flash memory is so trouble-free in operation... >>>>I've never found any *bad* flash memory, >>>>and I've ...

+ Reply to Thread
Page 2 of 2 FirstFirst 1 2
Results 21 to 22 of 22

Thread: AGFA SD card

  1. Re: speed measured (Was: Re: AGFA SD card)

    drocillo wrote:
    > Michael J. Mahon wrote:
    >
    >>drocillo wrote:
    >>
    >>>Michael J. Mahon wrote:
    >>>
    >>>
    >>>
    >>>>I think the problem is that flash memory is so trouble-free in operation...
    >>>>I've never found any *bad* flash memory,
    >>>>and I've never heard from anyone who wore some out!
    >>>
    >>>
    >>>Yes ! And the housing boom will last forever ! The prices will never
    >>>fall !

    >>
    >>In this case, more like, "The card will last longer than the camera!"

    >
    >
    > No. It is more like: "In the past 5 years, my house grew significantly
    > in price. Houses of everyone whom I know grew up in prices. Therefore,
    > everyone's house in the US grew up in price. The growth will be
    > indefinite".
    >
    > "My memory cards never failed. Cards of everyone around me whom I know
    > never failed. Therefore, nobody in the world had their memory cards
    > failed. In fact, the cards will never fail".


    Gee, and here I thought that we had reached a point of some
    understanding...

    Your analogy is false. My statements were not analogies, but facts.
    I have already experience my media outlasting my cameras several times.

    I have personally used them heavily for the last five years and
    have not experienced a single problem with data reliability. This
    is a reasonable base of experience to justify lowering my level of
    concern about them as a point of failure. I am much more concerned
    about physically losing one containing valuable pictures than I am
    about the card losing some data, and for both reasons, I never have
    data *only* on a card for more than a week. BTW, I have had data
    stored on these cards for years (redundantly) and have not observed
    any loss of data over this period, either.

    Unlike a potential real estate bubble, there is no mechanism which
    could lead to a catastrophic loss of much of the flash memory data
    in the world, the country, or even in my house--except physical
    destruction! (Which is why I believe in off-site archives.)

    In general systems design, there are four possible combinations
    of system inputs and outputs:

    1) Input signal is not present and is not detected.
    2) Input signal is not present and *is* detected.
    3) Input signal is present and is detected.
    4) Input signal is present and is *not* detected.

    While states 1) and 3) represent accurate behavior, all real
    systems are subject to errors, represented by states 2) (misdetection)
    and 3) (failure to detect). The negative consequences of error 2) can
    be as crippling as those of error 4).

    You accuse me of error 4--not detecting a problem that may exist
    in reality. But you are subject to error 2--detecting a problem
    that may not exist.

    Notice that we now have several years worth of experience with
    consumer-grade flash memory devices of various designs, and there
    is no outcry about failures or design problems. They work for the
    purposes for which they are intended. (Archival storage may not be
    one of those purposes!)

    I never said that they will never fail--of course, they will. But
    will anyone care if they are using them to: take pictures before
    transferring them to other media, store MP3s to listen to them
    portably, or even (as I do) use them to simulate a hard drive for
    an older, slower computer (with regular backups). If one type
    lasts 8 years and another lasts 16 years, and I will have replaced
    them all in less than 5 years, should I care?

    I view them as convenient, reliable (in practice), and, ultimately,
    disposable media that sells for less than the price of a good meal
    at a restaurant.

    Unless you are responsible for designing the next generation of
    flash memory, you would probably be well served by regarding them
    similarly.

    Now, if you were expressing worry about the practical life expectancy
    of today's so-called "archival" media, like recordable DVDs, I'm with
    you. ;-)

    BTW, have you checked your tires recently? How about your brakes?
    And how do you feel about riding in elevators? ;-)

    Using cumulative failure data to estimate future risk is an inductive
    process, and therefore cannot be certain. But is it the best way we
    have of making rational decisions, and it does not rule out hedging.

    Have a nice day.

    -michael

    Home page: http://members.aol.com/MJMahon/

    "The wastebasket is our most important design
    tool--and it is seriously underused."

  2. Re: speed measured (Was: Re: AGFA SD card)

    Michael J. Mahon wrote:

    > Notice that we now have several years worth of experience with
    > consumer-grade flash memory devices of various designs, and there
    > is no outcry about failures or design problems. They work for the
    > purposes for which they are intended.


    I have both my first degree and doctorate in semiconductor physics (I
    do not practise this occupation, though). I fabricated semiconductor
    microdevices by myself. Some of them failed later. The reasons were
    that e.g. I etched the semiconductor material too thin, or deposited a
    too thin layer of metal, or I inadvertently misaligned the mask when
    depositing contact layers. Or the wire contacts were not welded too
    well to the device. The device worked well in the beginning, but failed
    later, because too much current destroyed the paths which turned out to
    be too thin, or electromigration of metal into the semiconductor
    occured.

    So that I know that the chip which I am holding in my hands may well
    turn out to be a time bomb. All is going well, until one day the unit
    "tires". I am a perfectionist by nature, and I want to minimize to zero
    the amount of mishaps on me. Some manufacturers of semiconductor chips
    adhere better to the QA processes, and their chip designs are
    inherently better than those of other manufacturers (e.g. provide
    thicker paths, better alignment of masks, use of materials less prone
    to disintegration, incorporating less amount of elements which may fail
    etc). For example, the MLC chip has much more complicated architecture
    (=more elements), therefore it is more probable to fail than an SLC
    chip. Some manufacturers have their metal contacts made more sloppy
    (e.g. Taiwan-made Toshiba vs Japan-made Toshiba or China-made SanDisk).
    The probability of failure of contacts in the chip of _that_ particular
    manufacturer is higher.

    D.


+ Reply to Thread
Page 2 of 2 FirstFirst 1 2