failed to open /dev/btrfs-control, skipping device registration: No such file or directory

[David Hajes]

Description: Ubuntu 20.04.3 LTS
Release: 20.04

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btrfs-progs:
  Installed: 5.4.1-2
  Candidate: 5.4.1-2
  Version table:
 *** 5.4.1-2 500
        500 http://ch.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        100 /var/lib/dpkg/status

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created partition on all disks with fdisk.

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sudo mkfs.btrfs -d single --csum blake2b -L bt01_01 /dev/sde1 /dev/sdf1 /dev/sdg1 /dev/sdh1 /dev/sdi1 /dev/sdj1 /dev/sdk1 /dev/sdl1

btrfs created volume

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/etc/mkinitcpio.conf >> brtfs

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reboot

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brtfs module not loaded/used by anything

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modprobe -r brtfs

brtfs device scan
Scanning for Btrfs filesystems
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory
WARNING: failed to open /dev/btrfs-control, skipping device registration: No such file or directory

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lsblk -f

sde
└─sde1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4
sdf
└─sdf1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4
sdg
└─sdg1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4
sdh
└─sdh1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4
sdi
└─sdi1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4
sdj
└─sdj1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4
sdk
└─sdk1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4
sdl
└─sdl1 btrfs bt01_01 c6b60114-4b48-4659-8fcf-eb820fb1f8d4

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kernel wiki

 I get the message "failed to open /dev/btrfs-control skipping device registration" from "btrfs dev scan"

You are missing the /dev/btrfs-control device node. This is usually set up by udev. However, if you are not using udev, you will need to create it yourself:

# mknod /dev/btrfs-control c 10 234

/dev/btrfs-control already exists.

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no idea what is going on, it supposes to work from scratch. single device doesn't work either.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: btrfs-progs 5.4.1-2
ProcVersionSignature: Ubuntu 5.4.0-89.100-generic 5.4.143
Uname: Linux 5.4.0-89-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: pass
Date: Fri Nov 5 12:52:40 2021
InstallationDate: Installed on 2021-10-21 (14 days ago)
InstallationMedia: Ubuntu-Server 20.04.3 LTS "Focal Fossa" - Release amd64 (20210824)
ProcEnviron:
 SHELL=/bin/bash
 LANG=en_US.UTF-8
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
 PATH=(custom, no user)
SourcePackage: btrfs-progs
UpgradeStatus: No upgrade log present (probably fresh install)

[Ken Sharp (kennybobs)]

> /etc/mkinitcpio.conf >> brtfs

Did you really add brtfs instead of btrfs?

[David Hajes (hajes29a)]

I do not remember any more...test system doesn't work any more.

That would explain why it didn't work with this typo.

As they say, "99% of issues are between ground, and operated device/tool/whatever." ROFL