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USB Flash Drive Not Recognised

By weslstan
Feb 12, 2009
  1. LookinAround

    LookinAround TechSpot Chancellor Posts: 8,395   +169

    I believe some recent "state-of-the-art" flash devices meet new standards (don't recall for certain) but fyi
    • The Open NAND Flash Interface Working Group (ONFI) has developed a standardized low-level interface for NAND flash chips. It released its first spec Dec, 2006. Also
    • The Non-Volatile Memory Host Controller Interface (NVMHCI) Working Group includes a group of vendors, including Intel, Dell, and Microsoft. Its goal is to provide standard software and hardware programming interfaces for nonvolatile memory subsystems
    My last post didn't so-much focus on the OP's particular problem but rather on the topic of data recovery based on LUT failure. I, without doubt, agree no software can recover if, in fact, there's hardware damage (again back to my whole point of just addressing: hardware damage vs. data corruption) and not necessarily categorizing the OP's problem in this case.​
    just trying to add some info to the forums.....
     
  2. raybay

    raybay TS Evangelist Posts: 10,716   +6

    As with most baloney, it takes someone's willingness to believe... There has been a great deal of that on this subject that is not backed up by any of the technology reports.
     
  3. xehqter

    xehqter TS Rookie Posts: 85

    Most of what I know about USB flash drives comes from reverse engineering them or trial and error, honestly, there are so many ways these things can die I don’t bother diagnosing them anymore. It’s easier just to pop the chip and rebuild the data. Easier still requires a few hours of work, occasionally it will take 24hrs - 48hrs of work on more complex drives. Older drives < 1G are easier than larger drives, anything past 8G is a nightmare due to complexity.

    Controllers tend to be very sensitive to errors in the system area (ie: firmware, settings, lookup tables), errors in the user area are usually corrected by the ECC data or by remapping sectors otherwise "weird things" seem to happen. Flashboot.ru is your best shot at getting manufacture tools for flash drives, most of the tools are geared towards repairing your flash drive by wiping the data but it may be a start if you’re looking to get physical access to the data. Some of the tools claim to give you raw access but all I’ve seen is just the virtual environment the controller creates ie: Physical Access with WinHex. Nothing special.

    ONFI is trying to create a standard spec for NAND chips so device manufactures can buy memory from any manufacture without having to check that the clock or signals is the same. Some NAND manufactures deviate from the accepted spec by using a faster clock or changing the commands ever so slightly.

    NVHMCI to my understanding is to create a standard for better writing to SSD hard drives. NAND memory requires data to be written in blocks (usually 128K) and read in pages (2k) or blocks which differs from hard drives which can read and write on 512byte sectors. This adds extra overhead for the controller to emulate, the idea is reading and writing in a more optimized way will speed up SSD.
     
  4. xehqter

    xehqter TS Rookie Posts: 85

    data recovery companies & manufactures tend to protect their trade secrets. The same is true with hard drives. I still hear story's from people who think the way to stop clicking noises is to bang the hard drive on its side to knock the heads loose..
     
  5. LookinAround

    LookinAround TechSpot Chancellor Posts: 8,395   +169

    raybay, i honestly am not sure just who or whom or what you are referring to but I don't think anyone in this thread has been posting here to simply push what they believe is a line of "baloney"

    In fact, most everyone posting in the thread with an opinion on the topic (mine included) hasn't had all the I's dotted nor the T's crossed. But we're not exactly proof reading and double checking every iota of detail so we can publish in a professional technical journal either.
     
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