Proxmox won't boot with degraded btrfs RAID1

[adriano_da_silva]

In a standard installation of Proxmox version 7.3, the server was installed over a raid1 btrfs array of two mirrored disks. That was the boot disk. After working a few days, there was a problem with the hardware (probably) and the system crashed. Upon restarting, I noticed that one of the disks in the raid was not recognized by the hardware. The first of the HDD's is really broken. Luckily, the second one is working.

I believed that this would not be a big problem, after all a raid1 is for that. That's when I had the surprise: The system doesn't boot with just one disk, because it's in the "degraded" state.

When I turn on the server, it starts to boot but stops at the initramfs screen. From then on, I don't know how to proceed.

I tried to find it on the internet, but I didn't find a good tip for when the system has already been restarted with the raid degraded.

Question: Now that the system is stopped, how can I make it boot even though it is degraded, so that later I can replace the broken disk?

Tanks!

 

[Neobin]

Maybe this helps?:
https://forum.proxmox.com/threads/s...ot-after-removing-one-disk.108223/post-465250

 

[adriano_da_silva]

Maybe this helps?:
https://forum.proxmox.com/threads/s...ot-after-removing-one-disk.108223/post-465250

Thanks for the answer.

I had already found the publication of this link, but unfortunately it does not solve my case, because I no longer have the second disk working to boot and set the flags that it suggests. So the suggestion in that post would be to put "rootflags=degraded" on the kernel command line in /boot/grub/grub.cfg.

Or, placing it as permanent, change the content of the GRUB_CMDLINE_LINUX_DEFAULT="quiet" variable in /etc/default/grub to keep the same flags, leaving GRUB_CMDLINE_LINUX_DEFAULT="rootflags=degraded".

But in fact, I don't have access to this file in the initramfs. It does not mount internal root or /boot or even /etc.

So how could I put this parameter on grub startup? If it was the old (legacy) grub I think it would be easier. But since this is modern grub, I don't know how to do it without being able to boot and mount the root folder of the system that is locked inside the raid1 of the degraded btrfs.

That is, I can't mount raid1 to access the file where I would put the configuration and create the new grub configuration that would allow me to mount the degraded raid... Which comes first, the chicken or the egg?

If I could mount btrfs on the degraded raid1, I could rebuild raid1 using a fresh disk.

Please, would anyone know how to help?

 

[Dunuin]

As I had screwed up my initramfs preventing me from booting, I had to boot a Live Linux, mount the PVE root filesystem, then chroot into it, bind-mount some folders like /proc, /sys, /dev and so on and then rebuild the initramfs. The same should work with building a new grub, which I also did once in the past.

See here: https://forum.proxmox.com/threads/fix-stuck-initramfs.120192/#post-522569

 

[adriano_da_silva]

I tried to mount it from the Proxmox installation pen drive, but I couldn't, because it couldn't mount the degraded Btrfs. In theory, I would have to put the flags to allow this volume mounting in the Kernel line of the live Linux disk, I believe. It will be? How would you do that? Very complicated to recover the server in a moment of urgency.

 

[Neobin]

So how could I put this parameter on grub startup?

On-the-fly editing of and adding to the GRUB entry should be possible, no?:
https://docs.fedoraproject.org/en-U...sec-Making_Temporary_Changes_to_a_GRUB_2_Menu

 

[adriano_da_silva]

On-the-fly editing of and adding to the GRUB entry should be possible, no?:
https://docs.fedoraproject.org/en-U...sec-Making_Temporary_Changes_to_a_GRUB_2_Menu

Yes, it worked. Thanks!