[How To] How to convert Debian Wheezy from Ext3 or Ext4 to Btrfs

Normally the ones we use GNU / Linux we have used for our partitions the famous Ext2, Ext3 and Ext4, but as we know, there are other types of file systems and Btrfs is gaining quite a bit of popularity.

But what is it Btrfs? Let's see a brief description found in Wikipedia:

Btrfs (B-tree FS or usually pronounced "Butter FS") is a File System copy-on-write announced by Oracle Corporation for GNU / Linux.

Its objective is to replace the current file system ext3, eliminating the greatest number of its limitations, especially with the maximum size of the files; in addition to the adoption of new technologies not supported by ext3. It is also stated that it will "focus on fault tolerance, repair and ease of administration."

Well, in this article I will show you how to use debian wheezy with Btrfs, following the steps I found in this link. I think it goes without saying that if you decide to make the change, you must do so at your own risk and that I am not responsible for any catastrophe related to your data. Let's go there 😛

Going from Ext3 / 4 to Btrfs

1.- The first thing we must do is save all our data or better yet, do this test in a virtual machine.

2.- We download an .iso of Debian Testing and "burn" it on a CD or put it on a pen drive with UNetbootin to boot from this device.

3.- Although the original article does not clarify it, I suppose that we must install as is logical, and once we have the system ready we put:

fsck -f /dev/sdaX

(assuming / dev / sdaX is the root filesystem)

4.- We install our favorite editor and btrfs-tools (if not available).

5.- Then we execute:

btrfs-convert /dev/sdX

6.- Later:

mount /dev/sdX /mnt

Then:

mount -o bind /dev /mnt/dev
mount -o bind /sys /mnt/sys
mount -o bind /proc /mnt/proc

7.- We use Chroot:

chroot /mnt

8.- We edit the file / etc / fstab, we look for the line where the root (/) filesystem is mounted and we change UUID by / Dev / sd, we changed ext3 / ext4 by Btrfs, we change the option to 'defaults' and we change the last number (1) to 0.

For example, in my case it would be to change this:

UUID=c2bc3236-b089-4f1e-8303-8fc9fab8848f    /    ext4    errors=remount-ro 0   1

and leave it like this:

/dev/sdX    /           btrfs    default     0       0

9.- Then we execute:

ls -la /boot

With this what we do is show the files that are inside / boot making sure that we have one similar to this: initrd.img-3.2.0-2-686-pae. What we need is the text that comes after 'initrd.img-' which will be the Kernel that we will use in the following command:

mkinitramfs 3.2.0-2-686-pae -o /boot/initrd.img-3.2.0-2-686-pae

10.- Later we update the GRUB:

grub-install /dev/sdX
update-grub

When finished we use the command:

exit

To get out of chroot.

11.- We disassemble:

umount /mnt/proc
umount /mnt/dev
umount /mnt/sys
umount /mnt

12.- We restart and pray !!! 😀

If a catastrophe does not happen, we can verify that we are already in Btrfs doing the following checks:

1.- How root we execute:

update-initramfs -u -t -kall

2.- We change again in the file / etc / fstab el / Dev / sd by UUID. To watch the UUID from the partition we execute:

ls -la /dev/disk/by-uuid/ | grep sdΧ

Which should return something like this:

lrwxrwxrwx 1 root root 10 abr 19 08:50 0c3299fc-de7b-496f-8cf8-0d0945111b88 -> ../../sda5
lrwxrwxrwx 1 root root 10 abr 19 08:50 2cce04c7-ae67-413b-9773-afe86a36aa39 -> ../../sda6
lrwxrwxrwx 1 root root 10 abr 19 08:50 c2bc3236-b089-4f1e-8303-8fc9fab8848f -> ../../sda1

If everything went well, you can delete the backup that the conversion process has created (ext2_saved) as follows:

btrfs subvolume delete /ext2_saved

Done 😀