当您从闪存驱动器中删除所有内容并重新格式化时，您可能会认为选中时它应该“显示”为完全空，但情况并非总是如此。有鉴于此，今天的超级用户问答帖子给出了一个困惑读者问题的答案。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

照片由阿迪科斯（Flickr）提供。

问题

超级用户读者Andrew想知道如何在空的和新格式化的闪存驱动器上使用空间：

I recently purchased a SanDisk Cruzer CZ36 16GB USB 2.0 flash drive with FAT32 as the default formatting. I need to store files that are larger than four GB on this flash drive, so I decided to reformat the flash drive as NTFS. The flash drive also had some SanDisk SecureAccess software preloaded on it that I did not want. On my Windows 7 system, I right-clicked on the flash drive in Windows Explorer and selected Format. I did a full format by deselecting the Quick Format option.

After reformatting the flash drive, Windows tells me that it is not completely empty. If I right-click on the flash drive in Windows Explorer and select Properties, Windows gives me this information:

Why is this the case even though I just formatted the flash drive? Is this to be expected or are there some files still lingering on the flash drive? When I open the flash drive in Windows Explorer, no folders or files appear even though my system’s settings are configured to show hidden items. I find it worrisome that there is a total of 91.7 MB somehow being used on this supposedly “empty” flash drive.

空的和新格式化的闪存驱动器上如何使用空间？

答案

超级用户贡献者David Schwartz为我们提供了答案：

This is normal. An “empty” NTFS file system has a number of internal files such as the master file table (“$MFT”), the log file used for file system recovery (“$LogFile”), the volume descriptor file (“$Volume”), and so on.

The largest one is probably the cluster allocation bitmap (“$Bitmap”) that keeps track of the space that is used and the space that is free. This is pre-allocated when the file system is created.

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