Cloop
From Knoppix Documentation Wiki
Contents
Introduction
Cloop, is a [Kernel (computers)] [module] to add support for [filesystem-independent,] transparently decompressed, read-only, block devices.
Where to download
http://developer.linuxtag.net/knoppix/sources/
Use version 1.xx if you have a 2.4 kernel, or version 2.xx for 2.6 kernel. Versions 0.xx are too old, probably won't work well.
Installation
make KERNEL_DIR=/path/to/linux-kernel/sources
Issue these commands as root
mkdir -p /lib/modules/misc && cp cloop.o /lib/modules/misc/ depmod -a mknod /dev/cloop b 240 0
Usage
Creating a compressed image:
create_compressed_fs image blocksize > image.cloop_compressed
Where blocksize must be a multiple of 512 bytes. Make sure you have enough swap to hold the entire compressed image in virtual memory!
The command may also be used in Linux command line pipe sequences. Use "-" as the image filename. The dash, "-" will cause the command to read data from stdin, as in
mkisofs -r datadir | create_compressed_fs - 65536 > datadir.iso.compressed
Mounting a compressed image (see above for device creation):
insmod cloop.o file=/path/to/compressed/image
mount -o ro -t whatever /dev/cloop /mnt/compressed