从表面上看，操作系统的文件系统可能看起来像一大堆文件夹，但肯定还有更多的文件夹。请继续阅读，我们将调查文件系统表面下的内容。

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。

问题

超级用户读者P\u Q对文件系统很好奇，他写道：

I have used Windows since childhood, and when I hear the phrase “Windows files system” I think of directories (folders) within directories, a folder called SYSTEM, a folder called PROGRAM FILES, etc. Is this what the system is? Just the layout of the folders?

And then I recently started using Linux, and my reference book says in the Linux filesystem everything starts at root and branches off from there. How is that really different from Windows? I mean, it seems the Linux system and the Windows system are just two ways of setting up a directory tree. Is this what file system means?

这种简单的文件系统描述方式是最准确的吗？让我们再深入一点。

答案

超级用户贡献者tomwij**an对Windows和Linux操作系统中的文件系统结构进行了深入的研究。他写道：

Just the layout of the folders?

Sounds too good to be true…

Let’s take the FAT32 file system as an example. I can install Windows XP on it, but I can also use it on a memory card. On a memory card, you don’t have those folders that you sum up.

So… Don’t confuse the directory layout of a family of operating systems with a file system.

Is this what a file system means?

No… It refers to the underlying bits and bytes that make your directory structure work.

The underlying bits and bytes? Show me FAT32!

Let’s look at what FAT32 looks like, it has:

• Some header sectors in the beginning, like Volume ID and Reserved Sectors
• Two File Allocation Tables, allowing us to figure out where our files are.
• Clusters containing all our directory and file data.
• Some very **all unused space that we can’t use.

A FAT table c***ists of a lot of entries that look like this, allowing us to determine where the directory or file is stored in the clusters space, as well as some attributes and size.

A directory entry would point to a list of directory/file entries…

In the clusters space, we can now travel our clusters to find the data we need. A cluster essentially contains data and information where the next fragments are

Do other file systems differ? Show me NTFS!

I’m going to show you an image so you can notice the differences, the rest is homework for the reader: More information can be found on this blog archive or Google.

The main idea is that NTFS is a huge improvement over FAT32 that is more robust/efficient. Having a better idea of (un)used space by using a bitmap to further help against fragmentation. And so on…

What about the file systems on Linux? Show me ext2/3!

The idea is that ext2/ext3 use super blocks and inodes; this allows for soft and hardlinks, directories that are files, files with multiple names and so on. The main gist is abstracting away to allow the file system to be capable of doing more meta-ish stuff…

有关文件系统的更多阅读，请参阅以下How to Geek文章：

• HTG解释：Linux目录结构解释
• HTG解释说：您应该选择哪个Linux文件系统？
• 我的USB驱动器应该使用什么文件系统？

有什么要补充的解释吗？在评论中发出声音。想从其他精通技术的Stack Exchange用户那里了解更多答案吗？在这里查看完整的讨论主题。