precomp-cpp VS vdo

You should look at Precomp - an apparently abandoned, but awesomely working arhiver that is dedicated to compressing those ZIP-based formats, and compresses them twice-thrice as small as LZMA2 can.

You can also have a look at this packer. It compresses PDF and EPUB 2-3 times smaller than 7z at maximum settings, at half the speed. I keep all my books in it and never had a problem.

There is an opensource archiver called precomp that is designed specifically for e-documents and compresses them 2-3 times smaller than 7z in ultra mode. It works, and I keep my e-books in it. However, it seems nobody else does, and development has stopped due to lack of interest.

There are tools like preflate [1] or precomp [2] that guarantees a bitwise identical reconstruction, of course modulo bugs.

[1] https://github.com/deus-libri/preflate

[2] https://github.com/schnaader/precomp-cpp/ (which internally makes use of preflate)

You may use "precomp" in order to seek and uncompress those parts. Then you can use a better compression algorithm : http://schnaader.info/precomp.php

Precomp http://schnaader.info/precomp.php is a program which will seek compressed parts and decompress those parts in order to compress with another algorithm. This greatly improve compression ratio with the other algorithm.

This may be of help. (a255854 and d649919)

It is true that I have not had time to concentrate fully on this issue in the last days, and it is difficult for me to understand some of the subtleties of the subject (english is not my main language). I would like to thank you for your help and patience! I really appreciate it. FYI, I will continue to work on this issue and will update this topic. I've also asked the VDO development team to take a look at it and to tell me if they have any ideas, you can see that discussion here.

No problem, maybe someone else will read it and be able to clarify all of this. I also asked the question on VDO Github repository.

Still working on this project, I can now compile and run LVM VDO under Debian, which is a great thing (I shared the script here).

#!/bin/bash install_dependencies() { (( ${#} > 1 )) && { apt update apt install -y "$@" } || echo "No dependencies to install" } clean_dependencies() { (( ${#} > 1 )) && { apt autoremove --purge -y "$@" } || echo "No dependencies to remove" } clone_repo() { (( ${#} == 1 )) && { TEMPDIR=$(mktemp -d "${1/*\/}.XXX") git clone "$1" "${TEMPDIR}" && \ cd "$TEMPDIR" && pwd -P } } # First part : KVDO module install_dependencies git make "linux-headers-$(uname -r)" > /dev/null 2>&1 WORK_DIR="$(clone_repo https://github.com/tigerblue77/kvdo.git)" ( cd "${WORK_DIR}" && \ make -j"$(nproc)" -C "/usr/src/linux-headers-$(uname -r)" M="${WORK_DIR}" ) > kvdo_log 2>&1 cp "${WORK_DIR}/vdo/kvdo.ko" "${WORK_DIR}/uds/uds.ko" "/lib/modules/$(uname -r)" clean_dependencies git make "linux-headers-$(uname -r)" > /dev/null 2>&1 rm -Rf "${WORK_DIR}" # Second Part: VDO Module install_dependencies git make gcc uuid-dev libz-dev libdevmapper-dev libblkid-dev > /dev/null 2>&1 WORK_DIR="$(clone_repo https://github.com/dm-vdo/vdo.git)" ( cd "${WORK_DIR}" && \ make -j"$(nproc)" && \ make -j"$(nproc)" install ) > vdo_build_log 2>&1 clean_dependencies git make gcc uuid-dev libz-dev libdevmapper-dev libblkid-dev > /dev/null 2>&1 rm -Rf "${WORK_DIR}" # Last Part depmod modprobe kvdo modprobe uds

Update : the project is progressing and I managed to install VDO on Debian 11(.3) : https://github.com/dm-vdo/vdo/issues/47