Re: Debian Bullseye install btrfs raid1

[Nikolay Borisov <nborisov@suse.com>]

On 4.05.22 г. 12:23 ч., richard lucassen wrote:
> Hello list,
> 
> Still new to btrfs, I try to set up a system that is capable of booting
> even if one of the two disks is removed or broken. The BIOS supports this.
> 
> As the Debian installer is not capable of installing btrfs raid1, I
> installed Bullseye using /dev/md0 for /boot (ext2) and a / btrfs on /dev/sda3.
> This works of course. After install I added /dev/sdb3 to the / fs: OK.
> Reboot: works. Proof/pudding/eating: I stopped the system, removed one of the
> disks and started again. It boots, but it refuses to mount the / fs, either
> without sda or sdb.
> 
> Question: is this newbie trying to set up an impossible config or have I
> missed something crucial somewhere?

That's the default behavior, the reasoning is if you are missing one 
device of a raid1 your data is at-risk in case the 2nd device fails. You 
can override this behavior by mounting in degraded mode, that is
mount -odegraded

> 
> R.
> 
> Begin: Running /scripts/init-premount ... done.
> Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
> Begin: Running /scripts/local-premount ... [    6.809309] Btrfs loaded, crc32c=crc32c-generic
> Scanning for Btrfs filesystems
> [    6.849966] random: fast init done
> [    6.884290] BTRFS: device label data devid 1 transid 50 /dev/sda6 scanned by btrfs (171)
> [    6.892822] BTRFS: device fsid 1739f989-05e0-48d8-b99a-67f91c18c892 devid 1 transid 23 /dev/sda5 scanned by btrfs (171)
> [    6.903959] BTRFS: device fsid f9cf579f-d3d9-49b2-ab0d-ba258e9df3d8 devid 1 transid 3971 /dev/sda3 scanned by btrfs (171)
> Begin: Waiting for suspend/resume device ... Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... done.
> Begin: Running /scripts/local-block ... [   27.015660] md/raid1:md0: active with 1 out of 2 mirrors
> [   27.021181] md0: detected capacity change from 0 to 262078464
> [   27.036555] md/raid1:md1: active with 1 out of 2 mirrors
> [   27.042062] md1: detected capacity change from 0 to 4294901760
> done.
> done.
> done.
> Warning: fsck not present, so skipping root file system
> [   27.235880] BTRFS info (device sda3): flagging fs with big metadata feature
> [   27.242984] BTRFS info (device sda3): disk space caching is enabled
> [   27.249314] BTRFS info (device sda3): has skinny extents
> [   27.258259] BTRFS error (device sda3): devid 2 uuid 5b50e238-ae76-426f-bae3-deee5999adbc is missing
> [   27.267448] BTRFS error (device sda3): failed to read the system array: -2
> [   27.275696] BTRFS error (device sda3): open_ctree failed
> mount: mounting /dev/sda3 on /root failed: Invalid argument
> Failed to mount /dev/sda3 as root file system.
> 
> 
> BusyBox v1.30.1 (Debian 1:1.30.1-6+b3) built-in shell (ash)
> Enter 'help' for a list of built-in commands.
> 
> (initramfs)
> 
>