SquashFS

Squashfs (.sfs) is a compressed read-only file system for Linux. Squashfs compresses files, inodes and directories, and supports block sizes up to 1024 KB for greater compression. Squashfs is also free software (licensed under the GPL) for accessing Squashfs filesystems.

Squashfs is intended for general read-only file system use and in constrained block device/memory systems (e.g. embedded systems) where low overhead is needed. The standard version of Squashfs uses gzip compression, although there is also a project that brings LZMA compression to SquashFS [http://www.squashfs-lzma.org/] .

Uses

Squashfs is used by the Live CD versions of Debian, Finnix, Gentoo Linux, Ubuntu and Fedora and on embedded distributions such as the DD-WRT router firmware. It is often combined with an union mount filesystem, such as UnionFS or aufs, to provide a read-write environment for live Linux distributions. This takes advantage of both the SquashFS's high speed compression abilities with the ability to alter the distribution while running it from a live CD. Distributions such as Slax, Debian Live and Mandriva One use this combo.

As the on-disk format of SquashFS have not stabilized yet [http://www.nabble.com/Re%3A-Squashfs-mainline-status-p13174944.html] , it is not ready for long-term archival use (i.e. in cases where a tar file may be used).

See also

* List of file systems
* Comparison of file systems
* Cramfs is another read-only compressed file system
* zisofs is a transparent compression extension to the ISO 9660 file system
* Cloop is a compressed loopback device module for the Linux kernel
* e2compr provides compression for ext2

External links

* [http://squashfs.sourceforge.net/ Squashfs website]