[SOLVED] failed to mount /boot

greenleafvolatile · 2021-01-10 08:10:59

Hey,

Since yesterday my system wont boot sometimes (1 in 5 times it wont boot on avg).

Kernel version:

Linux 5.4.87-1-lts x86_64

What is see:

[FAILED] Failed to mount /boot
See 'systemctl status boot.mount' for more details.

Or

kernel:FAT-fs (sda1): bogus number of reserved sectors
kernel:FAT-fs (sda1): can't find a valid FAT filesystem 
systemd[1]: Failed to mount /boot
systemd[1]: Dependency failed for Local File System

The output of systemctl status boot.mount says

mount: /boot: wrong fs type, bad option, bad superblock ...

The output of df -Th:

Filesystem       Type      Size  Used Avail Use% Mounted on
dev              devtmpfs   16G     0   16G   0% /dev
run              tmpfs      16G  1.2M   16G   1% /run
/dev/mapper/root ext4      246G   15G  218G   7% /
tmpfs            tmpfs      16G     0   16G   0% /dev/shm
tmpfs            tmpfs     4.0M     0  4.0M   0% /sys/fs/cgroup
/dev/sda1        vfat      9.4G  136M  9.2G   2% /boot
/dev/mapper/tmp  tmpfs      16G   72K   16G   1% /tmp
/dev/mapper/home ext4      808G  4.8G  762G   1% /home
tmpfs            tmpfs     3.2G   20K  3.2G   1% /run/user/1000

The output of fdisk -l:

Disk /dev/sda: 232.89 GiB, 250059350016 bytes, 488397168 sectors
Disk model: Samsung SSD 860 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 54035992-A70E-1E48-B862-FB13CA1FC741

Device        Start       End   Sectors   Size Type
/dev/sda1      2048  19533823  19531776   9.3G EFI System
/dev/sda2  19533824 488397134 468863311 223.6G Linux LVM

My fstab:

# <file system> <dir> <type> <options> <dump> <pass>
/dev/mapper/root  /     ext4   defaults    0      1
/dev/sda1         /boot vfat   defaults    0      2
/dev/mapper/home  /home ext4   defaults    0      2
/dev/mapper/tmp   /tmp  tmpfs  defaults    0      0
/dev/mapper/swap  none  swap   sw          0      0

/dev/sda is a Samsung 860 .M2 drive with the latest firmware.

What I tried:

I booted into the usb installation medium and ran dosfsck -r /dev/sda1
Afterwards /boot is still not mounted sometimes.
What I am going to try next is backup up the contents of /dev/sda1 and remake the fs with mkfs.fat -F32 /dev/sda1 and copy back the contents.

All feedback appreciated. Very interested to learn what causes bogus number of reserved sectors.

Okay, I think I found the problem. Now this might or might not be related, but I booted twenty times, ten times with Linux Stable and ten times with Linux LTS. /boot failed to mount zero times with Stable and 3 times with LTS. Like I said, probably not related, but thought I'd mention it anyway.

When I was in rescue mode I saw, using lsblk, that /dev/sda1 was not pointing to the disk that has the /boot partition, but /dev/sb1 was! So, I'm gonna use a UUID in my fstab and see if that fixes things.

It appears fixed for now.

Last edited by greenleafvolatile (2021-01-10 13:56:09)

Head_on_a_Stick · 2021-01-10 10:25:06

greenleafvolatile wrote:

All feedback appreciated.

9.3GiB is far too big for an EFI system partition, 512MiB should be plenty even if you're mounting it under /boot.

I would personally use GRUB and mount the ESP under /efi but only mount it when necessary (ie, add the noauto option for that partition in /etc/fstab and keep /boot on the root partition) to protect the frangible FAT filesystem as much as possible.

Arch Linux

#1 2021-01-10 08:10:59

[SOLVED] failed to mount /boot

#2 2021-01-10 10:25:06

Re: [SOLVED] failed to mount /boot

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