Linux with Operating System Concepts

partition will contain an independent 
file system
unto itself. Multiple partitions may be 
placed on one physical device or a single partition could be distributed across multiple 
devices. The distribution of partitions to physical device(s) should be transparent to the 
user and, unless a device fails, it should be transparent to the system administrator as well.
10.4.1 File System Redefined
The term “file system” requires a more precise definition before we continue. To this point, 
we have referenced a file system as the collection of all storage devices available. That is, 
the file system contains all of the files and directories of our computer. Now we see that 
a specific device (e.g., an internal hard disk) is divided into logical sections called parti-
tions. Each partition stores a file system. Thus, the term “file system,” as applied thus far is 
inappropriate because in fact there are (most likely) multiple file systems making up your 
storage space.
From here on, we will refer to the collection of storage devices as the storage (or file) 
space and use the term “file system” to define what a partition stores. The file system now 
includes with it information such as a type, mount options, and mount point. Since parti-
tions can take on different types of file systems, a file space might comprise multiple file 
systems.
There are many reasons to partition the file space. First, because each partition is inde-
pendent of the others, we can perform a disk operation on one partition, which would not 

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Linux with Operating System Concepts
impact the availability of the others. For instance, if we wanted to back up one partition, 
we would want to make it inaccessible during the backup process. But the other partitions 
would remain accessible (as long as the partition we were backing up was not the root par-
tition). Second, we can establish different access options on each partition. One partition 
might be read-only, another might have disk quotas placed on the individual directories, 
and another might involve journaling. Third, partitions will also allow us to specify disk 
space utilization more carefully. Some partitions would be expected to grow in size while 
others would remain static in size.
The segmentation of the storage devices into partitions is done at a logical level, not 
necessarily at a physical level. For instance, if we have a single hard disk for our system, 
it would be logically divided into partitions, not physically. When we view the storage 
devices in /dev, we will see one specific disk device per file system. If our computer uses 
a SATA hard disk, we will see under /dev devices such as /dev/sda1, /dev/sda2, and /dev/
sda3. This should not be taken as having three SATA hard disks but instead that we have