Filesystem

A filesystem is a space where a user can save files. Filesystem drivers (which are confusingly also called "filesystems") usually live in your kernel. Some filesystems don't use block devices like harddrives, but instead get their data from the network or save it in RAM.

What filesystem should I use?
If you want to know what filesystem to use, then you are probably installing Gentoo and are wondering which filesystem best saves and serves your files to and from your harddrive. Although there are still a lot of choices, the number of them has just decreased dramatically anyway: there are a lot of filesystems which are not meant to install Linux on, or it is simply not what you want/need.

For example, consider NFS. It gives you access to files from a remote machine as if they were local files. That's definitely not a feature you need, and, when installing Gentoo, doesn't solve the issue of saving files, since you still need a filesystem to actually save the files on a harddisk. What you need is a filesystem which can handle block devices, like your harddrive (most storage media are block devices). The most popular filesystems, these days, are XFS, Ext3 and Ext4. Upcoming filesystems are Btrfs and Tux3, but these can be a bit unstable.

Special-purpose filesystems
If you're not simply installing Gentoo to make a desktop installation, then you are looking for a special-purpose filesystem.

Special-purpose block device filesystems
These are the filesystems with neat features. For example, DM-Crypt is a filesystem which encrypts data as it is saved. SquashFS is a read-only filesystem (in that you can't modify it later on, and if you want to change it you'll have to create a new filesystem) which can handle compressed data.

Virtual filesystems
Virtual filesystems are filesystems which don't "live" anywhere. If you save anything to them, the data can get discarded or saved elsewhere, depending on the implementation. Often-used virtual filesystems are unionfs and aufs. Generally, you won't have to bother about them. If you do need to, then you probably know what you are talking about anyway.

Nonpersistent filesystems
If a filesystem is nonpersistent, then any data saved into it will disappear automagically at some point, most likely during a reboot. Examples of these include tmpfs. You can also use your GPU's RAM as swap.

Network and distributed filesystems
You can get your files off a network just as well as you can get any data from a network. Hence, there are several filesystems which do exactly that. Some get and save their data from and to a central server, others distribute data and load over several machines, forming a storage cluster. Some central storage filesystems implement a common protocol like FTP to make it possible to mount FTP shares. Others use dedicated protocols, like NFS and Samba, which implements the SMB/CIFS protocol commonly found on Windows boxes.

Dateisystem Systemy plików