Unfortunately, this hasn’t gotten as much attention as I think it should, but vdo volumes are now officially supported as in-tree modules in kernel 6.9 and newer. If you don’t know what vdo volumes are yet, check this out (they’re really cool).

In my opinion, vdo is the best alternative to zfs‘s compression and deduplication on Linux, especially since its license is not incompatible, allowing it to receive a lot more support from developers for being released under GPL-2. I’ve been using it off and on for the last few months, and while I haven’t done any formal benchmarks yet, subjectively it seems to be a lot more effective for reducing space consumption than zfs ever was (zfs‘s compression worked great, but dedupe is hampered by unreasonable ram usage).

The kernel 6.9 requirement makes using vdo a little difficult in Ubuntu 24.04, which does have lvm libraries new enough to make vdo volumes, but not without upgrading the kernel to one newer than stock, since it’s pinned at kernel 6.8. Thankfully, you can add kernels from a 3rd-party rather easily, such as zen, liquorix, or xanmod (I have personally done all my testing with xanmod).

With a 6.9 (or newer) kernel booted, all you need besides lvm and thin-provisioning-tools is the userspace modules for maintaing a vdo volume, and those can be downloaded here: https://github.com/dm-vdo/vdo/releases/tag/8.3.0.71

They need to be compiled manually, but luckily it’s really easy. First, install required libraries and autotools, etc.

apt install -y build-essential uuid-dev libblkid-dev zlib1g-dev

grab the tar from the dm-vdo/vdo releases page and decompress it. Then, navigate to the folder and run:

make
sudo make install

The prefix is automatically set to /usr, so the executables are in /usr/bin:

ls -1 /usr/bin | grep vdo                                                                 

vdoaudit
vdodebugmetadata
vdodumpblockmap
vdodumpmetadata
vdoforcerebuild
vdoformat
vdolistmetadata
vdoreadonly
vdorecover
vdostats

With some accompanying man files:

/usr/man/man8/vdoaudit.8
/usr/man/man8/vdodebugmetadata.8
/usr/man/man8/vdodumpblockmap.8
/usr/man/man8/vdodumpmetadata.8
/usr/man/man8/vdoforcerebuild.8
/usr/man/man8/vdoformat.8
/usr/man/man8/vdolistmetadata.8
/usr/man/man8/vdoreadonly.8
/usr/man/man8/vdorecover.8
/usr/man/man8/vdostats.8

A bash-completion file for vdostats:

/usr/share/bash-completion/completions/vdostats

And 3 example files written in perl for monitoring space on a vdo volume:

ls -1 /usr/share/doc/vdo/examples/monitor                  
                                                                                              
monitor_check_vdostats_logicalSpace.pl
monitor_check_vdostats_physicalSpace.pl
monitor_check_vdostats_savingPercent.pl

(you can invoke them with perl /usr/share/doc/vdo/examples/$EXAMPLE_NAME.pl)

If you do any side-by-side benchmarks with vdo v. zfs, please leave a comment and let me know your results. I plan to do my own eventually, but if you get around to them before I do, I’d love to see your results!