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- :title: File Systems
- :description: How Linux organizes its persistent storage
- :keywords: containers, files, linux
- .. _filesystem_def:
- File System
- ===========
- .. image:: images/docker-filesystems-generic.png
- In order for a Linux system to run, it typically needs two `file
- systems <http://en.wikipedia.org/wiki/Filesystem>`_:
- 1. boot file system (bootfs)
- 2. root file system (rootfs)
- The **boot file system** contains the bootloader and the kernel. The
- user never makes any changes to the boot file system. In fact, soon
- after the boot process is complete, the entire kernel is in memory,
- and the boot file system is unmounted to free up the RAM associated
- with the initrd disk image.
- The **root file system** includes the typical directory structure we
- associate with Unix-like operating systems: ``/dev, /proc, /bin, /etc,
- /lib, /usr,`` and ``/tmp`` plus all the configuration files, binaries
- and libraries required to run user applications (like bash, ls, and so
- forth).
- While there can be important kernel differences between different
- Linux distributions, the contents and organization of the root file
- system are usually what make your software packages dependent on one
- distribution versus another. Docker can help solve this problem by
- running multiple distributions at the same time.
- .. image:: images/docker-filesystems-multiroot.png
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