Every hard disk may be divided into partitions, and each one contains a file system. While Windows® assigns a letter to each of these file systems (well, actually only to those it recognizes), GNU/Linux has a unique tree structure of files, and each file system is mounted at one location in that tree structure.
Just as
Windows® needs a C:
drive, GNU/Linux
must be able to mount the root of its file tree
(/
) on a partition which contains the
root file system. Once
the root is mounted you can mount other file systems in the tree
structure at various mount points within the
tree. Any directory below the root structure can act as a mount
point, and you can mount the same file system several times on
different mount points.
This allows for
great configuration flexibility. For example if you were to
configure a web server, it's fairly common to dedicate an entire
partition to the directory which contains the web server's
data. The directory which usually contains the data is
/var/www
and acts as the mounting point for
the partition. Also, a big /home
partition
should be considered if you plan on downloading a large amount of
software, store many work or personal documents and photos, music
files, etc.. You can see in Figure 6.2, “A Not Yet Mounted File
System” and
Figure 6.3, “File System Is Now Mounted” how the system looks before and
after mounting the file system.
As you can imagine, this offers a number of advantages: the tree structure will always be the same, whether it's on a single file system or extended over several dozen. This flexibility allows you to move a key part of the tree structure to another partition when space becomes scarce, which is what we are going to do here.
There are two things you need to know about mount points: