Filesystems

What is it?

A file system in Linux is the way in which files are stored, organized, and managed on a Linux operating system. It is responsible for managing the data on a storage device, such as a hard disk or solid-state drive, by dividing it into multiple sections or partitions. The file system determines the structure and organization of the files, as well as the methods used to access and modify them.

Info

The most commonly used file systems in Linux are the ext4, btrfs, and xfs file systems. The file system chosen depends on the specific requirements of the system, such as performance, scalability, and reliability.

Partitions and multiple file systems

In linux each filesystem occupies a disk partition. These are separated ā€œlogical drivesā€ or sections inside a single (or more) real drives, but appear as different drives to the OS. Data is stored into different partitions for many reasons, including security or backup.

lsblk provides a tree-like view of the storage devices and their associated partitions, making it easy to see the hierarchical relationships between the different components of the system’s storage.For a graphical interface gparted can be used to check out the partitions in a system.

Mounting filesystems

Different file systems are mounted on the filesystem tree. The mount points are just directories in which the new filesystem will live.

The utility mount is used for this task:

sudo mount /dev/sda5 /home #Mounts the filesystem in the sda5 device(partition) in /home
sudo umount /home #Dismounts the filesystem

This is a temporal way of mounting a filesystem and will get unmounted in reboot. In order to make it permanent, the etc/fstab file needs to be modified.

Add a new line to the file with the following format:

<device> <mount point> <file system type> <options> <dump> <pass>

For example, to mount the file system located at /dev/sdb1 with the file system type ext4 to the mount point /mnt/data, the line would be:

/dev/sdb1 /mnt/data ext4 defaults 0 0

More information is available in man fstab

Good to know

mounted alone, as well as df -Th will show all presently mounted filesystems

NFS

A special kind of filesystem is a Network File System. The Network File System (NFS) is a protocol that allows a computer to share its files with other computers over a network. NFS enables seamless access to remote file systems as if they were local, allowing users to access and manage files on remote systems with the same ease as they do on their own computer.

It has a server and a client side

Server

On the server, nfs runs a a daemon, and allows to share a directory in the serverā€™s filesystem via NFS (with a network address)

sudo systemctl start nfs # Starts the NFS daemon

On the /etc/exports file, the directories that are going to be shared are typed in. For example /projects *(rw) means that the /projects directory in the server will be shared (with read and write accesses).

Using exportfs -av notifies Linux of the changes. The NFS daemon can also be reset, and set to start on boot.

Client

On the client, the filesystem is mounted like any other (Is also possible to modify fstab to boot with the filesystem mounted)

sudo mount servername:/projects /mnt/nfs/projects