Arch Linux

LacrimasProfundere

Member

Registered: 2022-04-15

Posts: 7

PC Crash During System Update - Cannot Boot - Restore BTRFS Snapshot?

Edit: Have given up on recovery. Topic can be closed.

Hello, I'll try to keep this short. Any help greatly appreciated:

PC had a hard crash in the middle of a system update, had to force shutdown. On reboot systemd-boot only option is "reboot to firmware device" and goes to BIOS.
Booted from live USB, found that my root BTRFS partition didn't want to cleanly mount. Ran btrfs rescue zero-log and that seemed to clear that piece up, partition now mounts cleanly in read/write.
Mounted boot underneath root, chrooted in and ran bootctl install and bootctl update which seemed to go without error, but still no boot option appears for Arch on systemd-boot.

I'm currently booted into a live USB session, I'd like to restore one of my @ root snapshots but am having trouble understanding the process (I've tried reading several walk throughs online).

lsblk:

nvme1n1     259:0    0  3.7T  0 disk 
nvme0n1     259:1    0  3.7T  0 disk 
├─nvme0n1p1 259:2    0  500M  0 part 
└─nvme0n1p2 259:3    0  3.7T  0 part /mnt/Arch

ls /mnt/Arch/

@  @home  @log  @pkg

sudo btrfs subvolume list /mnt/Arch/:

ID 256 gen 2719623 top level 5 path @
ID 257 gen 2719598 top level 5 path @home
ID 258 gen 2719596 top level 5 path @log
ID 259 gen 2719596 top level 5 path @pkg
ID 261 gen 2466929 top level 256 path @/var/lib/portables
ID 262 gen 2466929 top level 256 path @/var/lib/machines
ID 263 gen 2719621 top level 256 path @/.snapshots
ID 3774 gen 2698409 top level 263 path @/.snapshots/3511/snapshot
ID 3775 gen 2698410 top level 263 path @/.snapshots/3512/snapshot
ID 3776 gen 2698412 top level 263 path @/.snapshots/3513/snapshot
ID 3777 gen 2698413 top level 263 path @/.snapshots/3514/snapshot
ID 3778 gen 2698415 top level 263 path @/.snapshots/3515/snapshot
ID 3779 gen 2698416 top level 263 path @/.snapshots/3516/snapshot
ID 3868 gen 2707648 top level 263 path @/.snapshots/3605/snapshot
ID 3881 gen 2708887 top level 263 path @/.snapshots/3618/snapshot
ID 3882 gen 2708888 top level 263 path @/.snapshots/3619/snapshot
ID 3883 gen 2708891 top level 263 path @/.snapshots/3620/snapshot
ID 3884 gen 2708893 top level 263 path @/.snapshots/3621/snapshot
ID 3885 gen 2708896 top level 263 path @/.snapshots/3622/snapshot
ID 3886 gen 2708897 top level 263 path @/.snapshots/3623/snapshot
ID 3887 gen 2708913 top level 263 path @/.snapshots/3624/snapshot
ID 3888 gen 2708914 top level 263 path @/.snapshots/3625/snapshot
ID 3889 gen 2708916 top level 263 path @/.snapshots/3626/snapshot
ID 3890 gen 2708917 top level 263 path @/.snapshots/3627/snapshot
ID 3902 gen 2710029 top level 263 path @/.snapshots/3639/snapshot
ID 3926 gen 2712790 top level 263 path @/.snapshots/3663/snapshot
ID 3950 gen 2715565 top level 263 path @/.snapshots/3687/snapshot
ID 3973 gen 2718211 top level 263 path @/.snapshots/3710/snapshot
ID 3974 gen 2718304 top level 263 path @/.snapshots/3711/snapshot
ID 3975 gen 2718424 top level 263 path @/.snapshots/3712/snapshot
ID 3976 gen 2718895 top level 263 path @/.snapshots/3713/snapshot
ID 3977 gen 2719004 top level 263 path @/.snapshots/3714/snapshot
ID 3978 gen 2719109 top level 263 path @/.snapshots/3715/snapshot
ID 3979 gen 2719213 top level 263 path @/.snapshots/3716/snapshot
ID 3980 gen 2719318 top level 263 path @/.snapshots/3717/snapshot
ID 3981 gen 2719425 top level 263 path @/.snapshots/3718/snapshot
ID 3982 gen 2719542 top level 263 path @/.snapshots/3719/snapshot
ID 3983 gen 2719596 top level 263 path @/.snapshots/3720/snapshot
ID 3984 gen 2719610 top level 263 path @/.snapshots/3721/snapshot
ID 3985 gen 2719611 top level 263 path @/.snapshots/3722/snapshot
ID 3986 gen 2719613 top level 263 path @/.snapshots/3723/snapshot
ID 3987 gen 2719614 top level 263 path @/.snapshots/3724/snapshot

I moved @ to @-Old, and then mounted my snapshot from yesterday to a new @ (ID 3950):

sudo mount -o subvolid=3950 /dev/nvme0n1p2 /mnt/Arch/@

I am a bit confused as to what to do at this point, from my understanding I need to now make this snapshot writeable, and set it as the default. I'm unsure if my fstab entry will also need updating, I'm referencing subvolume by name:
/etc/fstab:

UUID=6eda83ea-e2da-4766-979a-fa8ec4bda6df       /               btrfs           rw,relatime,ssd,space_cache=v2,subvolid=256,subvol=/@   0 0

Please let me know any other info that would be helpful.

Last edited by LacrimasProfundere (2025-07-02 12:21:02)

LacrimasProfundere

Member

Registered: 2022-04-15

Posts: 7

Re: PC Crash During System Update - Cannot Boot - Restore BTRFS Snapshot?

Edit: Topic can be closed unsolved. After adding linux boot entry still receive vfat fail.

Posting from my phone and will be going to bed soon, will update with more info in the morning.

Set a snapshot as new default subvolume and updated /etc/fstab, can confirm it is booting correctly in read/write. While still on live USB, arch-chroot into the drive and reinstalled linux-zen, and did a fresh install of standard "linux" kernel which I didn't have previously. On reboot systemd-boot still only shows linux-zen, and I get dropped into a root emergency shell stating /boot failed to mount as vfat is an unrecognized file type. While I was chrooted in, I made sure /boot was mounted.

Last edited by LacrimasProfundere (2025-07-02 12:22:03)