E2compr

e2compr is a modification to the ext2 file system driver in the Linux kernel to support online compression and decompression of files on file system level without any support by user applications.

What does e2compr do?

e2compr is a small patch against the ext2 file system that allows on-the-fly compression and decompression. It compresses only regular files; the administrative data (superblock, inodes, directory files etc.) are not compressed (mainly for safety reasons). Access to compressed blocks is provided for read and write operations. The compression algorithm and cluster size is specified on a per-file basis. Directories can also be marked for compression, in which case every newly created file in the directory will be automatically compressed with the same cluster size and the same algorithm that was specified for the directory.

e2compr is not a new file system. It is only a patch to the ext2 file system made to support the EXT2_COMPR_FL flag. It does not require you to make a new partition, and will continue to read or write existing ext2 file systems. One can consider it as simply a way for the read and write routines to access files that could have been created by a simple utility similar to gzip or compress. Compressed and uncompressed files coexist nicely on ext2 partitions.

Supported Linux Kernels

The latest e2compr-branch is available for current releases of 2.6 and 2.4 Linux kernels, but development is stalled. There are also older branches for older 2.0 and 2.2 kernels, which are more stable.

References

* [http://sourceforge.net/projects/e2compr Sourceforge e2compr project]
* [http://e2compr.sourceforge.net/ Sourceforge e2compr documentation]
* [http://sourceforge.net/projects/e3compr Sourceforge e3compr project page, ext3 compression, alpha]

See also

* cloop
* e3compr
* SquashFS
* zisofs