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Most of us have had by now a few USB sticks dying from natural causes... you unplug them (regardless, in my experience whether you've safely removed hardware) and the next time you plug them in, it is like you didn't. Nothing shows.

I'm curious - what actually happens to a flash drive when we say that a USB drive has died? Something short-circuits? Overburns? What?

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Before I'd say it actually "died", I would try to recreate the partition and reformat. Assuming Windows, right-click on My Computer > Manage > Storage > Disk Management. Hopefully, the computer has recognized the USB stick... if so, you should be able to create a new partition and format. I don't know for sure, but I think there is a limitation on the number of writes flash will perform, but it is probably different for each manufacturer. More info: en.wikipedia.org/wiki/Flash_memory#Memory_wear –  Scott Aug 13 '10 at 15:34
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When a USB dies it goes to Silicon Heaven, the same place where all the calculators go. –  w3d Aug 13 '10 at 15:58
    
@Scott - Yes, tis true, amongst other things. But thankfully, I've no drive which I wish to save here ... just curious, when one of them thing dies, what actually happens. –  ldigas Aug 13 '10 at 16:39

2 Answers 2

up vote 7 down vote accepted

Flash memory cells use floating gate transistors to store each bit. The "floating" part of semiconductor is surrounded by an oxide and acts like a reservoir for electrical charge. Electrons can be "tunnelled" into or out of the floating gate (through the oxide), by applying the appropriate voltage. Otherwise the charge is stuck in the floating gate, even when the power supply is removed. However, over time (after many program-erase cycles) this oxide can wear down, and the cell loses its ability to store a bit.

The controller of a flash storage device might anticipate this problem and can replace worn areas of memory with spare area. This, along with a wear-levelling strategy, should prolong the life of the drive.

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So, it's something like a avalanche at a zener diode effect ? –  ldigas Aug 13 '10 at 16:42

From eHow.com:


Causes of Flash Drive Failure:

Mistreatment

A flash drive can be mistreated to the point where it fails. For example, if you plug your flash drive in and remove it incorrectly, then you may be putting an unnecessary amount of pressure on it, causing weakness in the solder joints. Or if you bump the flash drive while it is inserted in the computer, you can bend it at the solder joints. This can crack the solder joints, severing the connection and causing the flash drive to fail. Flash drives are relatively fragile, especially the connection between the USB connector and the flash circuit board.

Computer Failure and Power Surge

If a computer fails while a flash drive is plugged in to a USB port, the flash drive may fail as well. Or if a power surge occurs while a flash drive is plugged into a computer, this may also cause the flash drive to fail. While many flash drives can survive these occurrences, it is important that you understand that such an event could potentially cause harm to an attached flash drive and the data stored on it.

Virus Attacks

If a host computer is attacked by a virus while a flash drive is connected, then the flash drive will also be subject to attack and may become damaged. The data stored on the flash drive, then, may become corrupted or otherwise damaged or erased in the process.

Read and Write Cycle Loss

Flash drives all fail over time because there are only a finite number of read and write cycles available on them. So over time, a flash memory drive will simply wear out and need to be replaced. The memory chip inside the flash drive will fail through repeated use, but very few make it this far because they are susceptible to so many other forms of damage.

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This article is also useful. As a main reason for failures, it points out "manufacture defect": One reason why a USB flash drive can fail is due to manufacture defect. All flash memory is made in China and to keep costs down for themselves as well as the market, the manufactures are constantly trying to find ways to cut costs. These cuts can sometimes mean that the quality of a USB can go down; making it much more likely to fail or break. –  Mehper C. Palavuzlar Aug 13 '10 at 15:47

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