Btrfs / Snapper: Amazing Stuff!

karlmistelberger · October 31, 2019, 11:02pm

I gave btrfs a try when assembling a small desktop with a i3-4130 with 8 GB RAM and a WD20EZRX 2 TB ‘Green’ HDD. I did a LEAP 42.1 default install and gave it to a Linux newbie. Performance of btrfs was poor and it did not work out at all: https://forums.opensuse.org/showthread.php/516753-Corrupted-BTRFS

Now I gave btrfs another try on a i3-4130 with 16GB RAM and a SSD 850 EVO 250GB. Installing Tumbleweed on the machine with doubled RAM and SDD instead of HDD resulted in a totally different experience during the last year:

performance is good
system is virtually maintenance free
deletion of unneeded snapshots is extremely fast
balancing works like a charm
recover from full disk does work: https://ohthehugemanatee.org/blog/2019/02/11/btrfs-out-of-space-emergency-response/

Current status after running some massive ‘zypper dup’, deleting all but the last snapshot and running btrfs-balance.service:

linux-udd7:~ # btrfs filesystem usage /|head -6
Overall:
    Device size:                  40.00GiB
    Device allocated:              7.54GiB
    Device unallocated:           32.46GiB
    Device missing:                  0.00B
    Used:                          6.92GiB
linux-udd7:~ #

Given this pleasant experience I decided to further maintain the system as a backup and gradually add the software installed on the primary system using ext4. When done I plan to use btrfs as the primary system and ext4 as a backup.

knurpht · October 31, 2019, 11:21pm

I was not an early adapter of btrfs, but since I have my current laptop I’ve used it without any issues. And I do use the rollback feature a lot: install software to help support others, when done, rollback and I have my own clean TW back.

karlmistelberger · November 2, 2019, 6:07pm

That made me try ‘snapper rollback 2’. After rebooting changes made to network configuration were perfectly undone without any hassle whatsoever.

I will speed up my efforts to fully configure btrfs backup system and switch to using it as my primary system.

karlmistelberger · October 27, 2020, 7:36am

2016-08-16: first install on /dev/nvme0n1p2 ext4
2019-11-08: new install on /dev/sdc5 btrfs, manually installed packages installed already on /dev/nvme0n1p2. Kept ext4 as backup system
2020-05-17: replaced ext4 on /dev/nvme0n1p2 by new install using btrfs
2020-10-26: rsynced /dev/sdc5 to /dev/nvme0n1p2 and reinstalled bootloader. /dev/nvme0n1p2 is now primary system and /dev/sdc5 backup.

tsu2 · October 27, 2020, 8:56pm

Next time
Instead of manually building a duplicate system on BTRFS by hand,

You can instead
Clone your original system
Use the btrfs-convert utility to convert your ext4 to btrfs
https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-convert

Possible benefit of a new install vs cloning and converting is that you’ll get the latest recommended disk layout.

TSU

karlmistelberger · October 28, 2020, 6:55am

Main benefit of a new install is the creation of subvolumes used by the system partition: https://doc.opensuse.org/documentation/leap/reference/html/book-opensuse-reference/cha-expert-partitioner.html#sec-yast-btrfs-subvolumes.
Cloning the system to a new install is pretty fast with rsync skipping unchanged files and can by undone by ‘snapper rollback’ if something went wrong.
Using btrfs-convert is a nice option for data partitions such as /home, but I can’t see whether it will be useful for system partitions.

Being a newbie regarding btrfs I preferred the manual install to cloning in 2019-11-08. Doing it again I would go with new install plus cloning.