As I still get questions from my friend on how to use ntfs2btrfs, I decided to condense everything in a blog post (because I hate repeating myself too many times).

Installing ntfs2btrfs

This is probably the easy part: there’s a package of it on just every major repo.

Just install it like so:

  • Debian and Ubuntu: sudo apt install ntfs2btrfs
  • Arch: sudo pacman -Syu ntfs2btrfs
  • Fedora: sudo dnf install ntfs2btrfs

Or, if not available, download and compile it from the repo.

Using ntfs2btrfs

A word of warning: while the script has worked fine for two of my disks without data losses: please, for the love of god, backup your truly important data. You’ve been warned.

While your disk is unmounted (you can do that from your file manager by right clicking the drive), just call the program like so sudo ntfs2btrfs /dev/sda1.

Obviously, you need to replace /dev/sda1 with your correct drive: with a simple lsblk, you can print all your drives and their device name.

For example, this is the output from my PC:

❯ lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda           8:0    0   1,8T  0 disk 
└─sda1        8:1    0   1,8T  0 part /media/hdd
sdb           8:16   0 465,8G  0 disk 
└─sdb1        8:17   0 465,8G  0 part /media/ssd
zram0       253:0    0  15,5G  0 disk [SWAP]
nvme0n1     259:0    0 465,8G  0 disk 
├─nvme0n1p1 259:1    0     2G  0 part /boot
└─nvme0n1p2 259:2    0 463,8G  0 part /var/cache
                                      /var/log
                                      /var/tmp
                                      /srv
                                      /root
                                      /home
                                      /

Let’s say i want to convert my 465G drive (my very slow SATA ssd), i would call ntfs2btrfs like so sudo ntfs2btrfs /dev/sdb1.

Waiting

This conversion does take a while, and you will probably notice some warnings about files with extended permission not being supported: they are completely safe to ignore, as the data will get carried around, just without those extra permissions.

Profit

Congrats, you now have converted your drive to BTRFS! But are we truly done?

Space cache v2 & block group tree

This script is really nifty, but it doesn’t enable space cache v2 and block group tree: in short, if you have a slow and big drive (for example, a 2TB HDD), without this it will take a lot of time to mount your drive. And the boot process could even fail, because timeouts (ask me how I know lol).

How to convert to it

Firstly, I will assume you know how to mount your disk normally (see the CachyOS wiki if you don’t know how).

You will need to simply mount your drive with space_cache=v2 as an additional parameter.

For example, for my HDD I would have to go from this

UUID=1554bd55-3b4f-f451-bcd3-b00f3f847e27 /media/hdd     btrfs   defaults,noatime,commit=120 0 0

to this

UUID=1554bd55-3b4f-f451-bcd3-b00f3f847e27 /media/hdd     btrfs   defaults,noatime,commit=120,space_cache=v2 0 0

Then just do sudo systemctl daemon-reload and sudo mount -a.

Now, unmount your drive again and run

sudo btrfstune --convert-to-block-group-tree /dev/sda1

If you don’t have btrfstune, you’re probably missing the package btrfs-progs

Then, you’re done and you can just sudo mount -a your drives again!

Compression

BTRFS supports file compression: this is huge for things like your game drives, as some older games don’t employ asset compression and compressing them will save you some space.

To enable it, just add compress=zstd to your mount parameters like so:

UUID=1554bd55-3b4f-f451-bcd3-b00f3f847e27 /media/hdd     btrfs   defaults,noatime,commit=120,space_cache=v2,compress=zstd 0 0

And then, again, remount your drive with sudo systemctl daemon-reload and sudo mount -a.

Congrats, you now have enabled compression for your written files from now on!

Compressing already existing files

For your already existing files, you’ve got to use the defragment utility of btrfs while the drive is mounted.

Be warned that this process will take a lot of time, as it has to read and write each file that needs to be compressed.

sudo btrfs -v filesystem defragment -r -czstd /mnt/hdd

Checking savings

There’s compsize that accept as a parameter a folder or file on a BTRFS drive, and it will tell you it’s disk usage and compression ratio. Taking as an example my Payday 2 folder

❯ sudo compsize "/media/hdd/Giochi/Steam/steamapps/common/PAYDAY 2/"
Processed 13683 files, 663952 regular extents (663952 refs), 7252 inline.
Type       Perc     Disk Usage   Uncompressed Referenced  
TOTAL       61%       52G          85G          85G       
none       100%      6.1G         6.1G         6.1G       
zstd        59%       46G          79G          79G

you can see that’s quite the saving: 33G!

Some notes about compression

The algorithm I used in this article, zstd, is really fast: in it’s default state, it uses a compression level of 3. You shouldn’t be worrying about perfomance losses.

But if you really, really think that you have a potato PC, you can switch from zstd to lzo by just changing it in the /etc/fstab and in the filesystem defragment command. Be warned that it achieves worse compression ratios though!