Ubuntu – btrfs snapshot management

I did not know if there was anything that did this so I whipped up some code to achieve exactly what you want using my repository here: http://github.com/robertmassaioli/config-files

I have a file that says where all of the files belong and the generate_links program just puts them all there. If you know what you are doing and can compile some Haskell code then it is really simple and easy. Though be warned that it really was made for my own personal use.

What is the correct command to create a snapshot of my home partition on Ubuntu 12.04?

Given the fact that home is on a btrfs partition and it is mounted as /home, the correct command is:

sudo btrfs subvolume snapshot /home/ /home/<any_name_you_choose_for_the_snapshot>

Here are my results:

Before running the command today:

$ btrfs subvolume list /home  
ID 256 top level 5 path @home  
ID 257 top level 5 path @home/@snapshot_20120521_1936

The command:

$ sudo btrfs subvolume snapshot /home/ /home/@snapshot_20120611_1307  
Create a snapshot of '/home/' in '/home/@snapshot_20120611_1307'

After running the command today:

$ btrfs subvolume list /home  
ID 256 top level 5 path @home  
ID 257 top level 5 path @home/@snapshot_20120521_1936  
ID 258 top level 5 path @home/@snapshot_20120611_1307

The only issue with this method is that snapshots show up when you ls (list) /home.

The Ubuntu community Wiki has been updated with a solution for this. Here it is:

How to work with snaphots in Ubuntu's layout

In order to work with snapshots of / or /home in the Ubuntu layout it is very convenient to mount the btrfs filesystem at a separate location, and work from the top of the btrfs tree, rather than from the mounted subvolumes. <-- that is the solution. Unfortunately, it is not convenient.

sudo mount /dev/sdX# /mnt

To create a snapshot use the same syntax I used above:

sudo btrfs subvolume snapshot /mnt/@ /mnt/@_snapshot

This will create a snapshot of the @ subvolume named @_snapshot located also in the top of the btrfs tree. Since it is in the top of the tree, it will not show up when listing files in a mounted volume.

To roll back to a snapshot, you simply need to change its name to the name that ubuntu mounts and reboot. Here's how to change the name:

sudo mv /mnt/@ /mnt/@_badroot
sudo mv /mnt/@_snapshot /mnt/@

To delete a snapshot use:

sudo btrfs subvolume delete /mnt/@_badroot

btrfs snapshots are subvolumes in themselves, and self-contained, deleting the old @ subvolume like this is fine, provided we have a replacement.

NOTE: The btrfs-tools command set-default will break Ubuntu's layout.