當你不安全地彈出USB媒體時，Windows會很生氣，但這真的有關係嗎？如果您從未安全地彈出USB驅動器和其他基於快閃記憶體的媒體，最糟糕的情況是什麼？

今天的問答環節是由SuperUser提供的，SuperUser是Stack Exchange的一個分支，是一個由社群驅動的問答網站分組。

問題

超級使用者讀者西蒙真的很好奇，如果他從來沒有安全地彈出他的媒體，命運會降臨到他身上：

Quite often when I’m in a rush, I automatically pull out a USB pendrive or USB cable from an external hard drive from my desktop PC or laptop, without right-clicking on the safely remove icon in the system tray and unplugging via this route. So far nothing untoward has happened every time I have “been in a rush”.

What is the rationale behind right clicking on the safely remove icon and can I really lose information on USB media if this is not carried out ?

Is the [probability] of losing such information greatly increased, if the USB media is still flashing at the time of pulling it out of the computer (as opposed to non-flashing) ?

西蒙賭了多少錢？

答案

超級使用者貢獻者Dave Rook解釋道：

Yes it can, it’s about what happens if you remove the device when it’s in use (reading or writing):

When you plug in a USB drive, you give your PC free rein to write and read data from it; some of which is cached.

Caching occurs by not writing information immediately to the USB device, and instead keeping it in your PC’s memory (RAM). If you were to yank the USB drive out of your PC before this information is written, or while its being written, you’ll end up with a corrupted file.

However, Windows automatically disables caching on USB devices, unless you specifically say that you want it enabled. For the most part you don’t have to click the ‘Safely Remove Hardware’ button, if you aren’t writing or reading anything from the device.

Its there simply as an extra level of security preventing you from destroying your own files.

Doing so causes the files to close “gracefully”, preserving data, pointers and file size indicators. When writing to disk the computer doesn’t always “flush” a buffer and only part of the data may have been written. Using the proper procedure will assure that the data and pointers are in good shape.

Source

MSalters提供了一個清醒的見解：

A second reason is that flash drives need to have stable power for ~0.25 seconds after a write command. This is a fundamental physical problem, due random factors some writes may leave a logical 1 bit in a electrical 0.72 state. The fix is easy: just rewrite the bit, perhaps even a few times. Eventually it will stick.

If you’re really unlucky, the bit falling over will be in a filesystem table and corrupt e.g. an entire directory.

換句話說，不值得賭博哪一位可能或不被損壞：它可能是可移植應用程式快取中的臨時檔案，或者可能是MSALTER指出的關鍵系統檔案。

有關安全媒體彈出的更多資訊，請檢視：HTG解釋：您真的需要安全地移除USB棒嗎？

有什麼要補充的解釋嗎？在評論中發出聲音。想從其他精通技術的Stack Exchange使用者那裡瞭解更多答案嗎？在這裡檢視完整的討論主題。