What is a file system?
A file system (or filesystem) is an abstraction to store, retrieve and update a set of files. The term also identifies the data structures specified by some of those abstractions, which are designed to organize multiple files as a single stream of bytes, and the network protocols specified by some other of those abstractions, which are designed to allow files on a remote machine to be accessed.
Android supports different file systems:
- FAT: Used mainly for SDCards. This system is supported by most operating systems (Windows, Linux, Mac, etc.), which is why it's used for these "exchangeables". But it is also quite restricted, which is why it is rarely used somewhere else.
- exFAT: sometimes used instead of FAT -- but not generally supported
- extfs: The extended file system already has seen several generations. Android devices usually support ext2, ext3, and in most cases also ext4.
- YAFFS: A Log structured file system designed for NAND flash, but also used with NOR flash. This was often used for e.g. the
/datapartition with many devices up to Android 2.x
There are also some pseudo-filesystems used on Unix/Linux system in general and on Android devices in special:
- devfs: Virtual file system for managing devices on-the-fly
- procfs: Pseudo-file system, used to access kernel information about processes
- sysfs: Virtual file system holding information about buses, devices, firmware, filesystems, etc.
This list is not complete, but just gives a short overview over the most important items. For a more complete list of overall available file systems, please see Wikipedia.
- file-management: About managing your files on Android
- files: other file related issues
- mount: the command to make a file system accessible
- ntfs: NTFS is a Windows file system usually not supported by Android devices.
- partition: a division of either your internal storage or your sdcard. Usually, a partition is formatted -- and if so, it holds a file system.
- storage: where your apps and data are stored. This is the most generic term in this context, as it might refer to your sd-card as well as to the devices internal-storage, to a partition, or even to the cloud...