Arch Linux

smichaels

Member

Registered: 2019-07-25

Posts: 1

BTRFS Snapshot Exclusions

I am currently trying to set up an Arch install on BTRFS, which I am only somewhat famliar with. I am particularly interested in creating bootable snapshots so that I can roll back my system if I break something while experimenting or upgrading. However, I'm running into a problem: there doesn't seem to be any consensus on what subdirectories of  / need to be included in a snapshot in order to ensure that the snapshot will work properly if booted to.

According to this page, OpenSUSE (which has bootable snapshots by default) excludes /home, /opt, /root/, /srv, /tmp, /usr/local, and /var. The BTRFS Sysadmin guide, however, specifically says /var shouldn't be excluded; only some subdirs of it should. The Arch wiki itself does not comment much on subvolume layout, and I can't find any other authoritative sources on the topic. /tmp is the only subdir I'm 100% sure can be left out.

In short, what should and should not be included as part of my snapshots of /, providing that the snapshots' chief purpose is to be able seamlessly roll back to a previous system state if I break something? I realize this question extends beyond Arch itself to some extent, but I know there are at least a few directories of note that are Arch-specific and need to be taken into account (e.g. /var/lib/pacman").

Last edited by smichaels (2019-07-25 01:21:07)

ratcheer

Member

Registered: 2011-10-09

Posts: 924

Re: BTRFS Snapshot Exclusions

I'm a longtime btrfs user on Arch, and I have never considered this line of thought. I just make full snapshots of / and they have never let me down. My /home is a separate subvolume, which I also make full snapshots of.

As to subvolume layout, I use the "flat layout" as documented in the btrfs wiki.

https://btrfs.wiki.kernel.org/index.php … Guide#Flat