21 Jan 07
Partitions in Linux
Linux uses disk partitions similar to Windows in some ways. It accepts the standard 4 primary partitions per physical drive. Also like Windows, you can give up one primary partition and make an extended partition, which can have many logical partitions on it. That is where the similarities end and the differences begin.
In Windows, each partition is referred to by a drive letter, such as C: or D:. Linux refers to partitions much differently. Behind the scenes, Linux gives each partition a device identifier, such as /dev/hd0a. Each drive increments the number in the designation, so the first hard drive is always /dev/hd0, the second is /dev/hd1, and so on. Each partition on that drive, whether primary or logical, increments the letter at the end. So, the first partition would be /dev/hd0a, while the second partition would be /dev/hd0b. Still with me?
Now, in order to access the partitions, they need to be mounted to an empty folder. So, at boot, one of the partitions is designated as the root partition, or "/". That partition will have several folders in it, such as /home, /usr, and /var. You can mount any partition in any empty folder, and then access the data in the partition simply by going to that folder. For example, it is common practice to mount the folder that you put your personal documents into in the /home folder. Then, you can get to those documents simply by opening the /home folder. Don't worry if this is confusing, most of this is done behind the scenes and configured during installation. After installation, the system will read the /etc/fstab file to mount your partitions automatically.
Linux only requires one partition, but you have the option of using more. You can put / on a partition that is big enough for your entire operating system and all files and just run everything from there, or you can spread the operating system and files across as many partitions and disks as you like. Next, I'll go over several of the folders located in / and describe what they are and why you might want to put it on its own partition.
28 Jan 08