How files on sd card are overwritten?

pls give the exact explanation on how the deleted files on sd card are overwritten and if you save any new files is it a rendency to overwrite deleted files?
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  1. I feel like I came into the middle of a conversation here...

    Might try posting your question in the Flash Media forum

    As far as I know, deleted files on an SD card are overwritten in the same manner as files on any FAT32. That is, the space is made available to any new files, but the data is not actually overwritten or removed - only the filename and entry in the File Allocation Table are removed.

    And yes, any new files will have a tendency to use the location that held deleted files. If you want to recover a deleted file, works fine if you haven't written anything else to the drive. The more files written afterwards, the less chance of recovery.

    If you are trying to recover a deleted file, you might try any of the programs for this purpose and see if they work on SD media. And they should.
    Here is a popular free program:
    To see more programs, choose File Management from the menu path at the top of that page.
  2. Very different from a hard disk drive, as soon as the SD is reasonably recent and its controller tries to use all Flash locations evenly.

    Then, the controller onboard the Flash (SD, CF and all others) fools the OS and chooses by itself what location it will use next. It keeps an equivalence table on the card.

    So the user (the OS) has no way to impose the next location used. Flash-optimized OS (Vista) tell the Flash controller which locations are free, to help it optimize the write process.

    This has heavy implications on secure wiping. Algorithms developed for Hdd don't work at all - this may have fooled several professionals in the Clearstream affair.

    The only way I know is to saturate the card's capacity, in order to guarantee (provided there is no spare location...) that every free sector has been overwritten.
  3. Interesting info! So let's hope those programs that promise to clean-sweep SDs know how they differ.

    Saturation's followed by re-partition and format's the only method I've ever fully trusted. I remember the hubbub when the Justice Dept got with Norton to provide non-functional copies of their software to criminals.

    Of course, there's nothing like the satisfaction that comes from disassembling a hard drive and using the platters for target practice! And they make much better wind chimes than CDs.
  4. SD Card (Secure Digital Card) is a flash memory card widely used by digital cameras. The capacities are from 8 MB, 32 MB, 64 MB, 256 MB, 512 MB, 1 GB, 2 GB, 4 GB to 8 GB, and types include SD memory card, miniSD, SDHC, microSD. SD card is developed by SanDisk, Toshiba and Panasonic. SD card is compact and slim but handles high volume content.
    Now most of Digital devices store the data with SD card, for instance: digital camera, Mobile Phone and Palm.
    But sometimes you may lose the Photos or other files in SD card if you press the wrong button or the SD card is formatted.

    AppleXsoft Mac Photo Recovery:
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