scanning for btrfs file systems on system startup

Well, btrfs is typically included in the initramfs, thus one needs to $ update-initramfs -u, for the tools to be removed from the initramfs and thus stop affecting startup.

after executing

$sudo apt-get remove btrfs-tools

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
  btrfs-tools
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 2,508 kB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 247597 files and directories currently installed.)
Removing btrfs-tools (3.12-1) ...
update-initramfs: deferring update (trigger activated)
Processing triggers for man-db (2.6.7.1-1) ...
Processing triggers for initramfs-tools (0.103ubuntu4.2) ...
update-initramfs: Generating /boot/initrd.img-3.13.0-32-generic
W: TMPDIR is mounted noexec, will not cache run scripts.
Processing triggers for libc-bin (2.19-0ubuntu6) ...

in the last third line it updates initramfs

Any way I used $ update-initramfs -u, it had no effect.

Strange. Can you provide output of

$ uname -a

And attach your initramfs (/boot/initrd*), and /var/log/boot.log?

Output of $ uname -a

Linux infinite-darkness 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

The same issue here. I also upgraded from 12.04 (yesterday, so packages are most recent).

I have a fresh 14.04 installation. I did set up a single partition as btrfs, with 2 subvolumes for / and /home, so removing brtfs-tools is out of question.

The "Scanning for btrfs file systems" appears early on, but stays there for some 25 seconds until the boot resumes again.
The system finally boots and works fine afterwards, but the boot is definitely slow. There must be a bug causing this delay.

We have the same problem as João Manuel.
Fresh ubuntu 14.04 installation on laptop.
One disk partitioned as follows:
   /dev/sda1 ext4 /boot
   /dev/sda2 btrfs /
   /dev/sda5 btrfs /var
   /dev/sda6 swap
   /dev/sda7 btrfs /home

The message "Scanning for btrfs file systems" appears on boot and takes long time in there.

Same for 16.04, using the mini.iso on a KVM machine.

At first boot after installation, I get the message

"Scanning for Btrfs file systems"

with no progress.

Note that I installed ubuntu 16.04 using btrfs partition /dev/vda2 during installation. Actually, I _want_ btrfs to be used, but ubuntu can't find the partition it is installed on. The partition itself is fine (checked with gparted from an SystemRescueCD). Still, I get this message.

When I try to boot into the ubuntu installation from the SystemRescueCD 4.7.3, I get a

[...]
Attempting to mount device: /dev/sda2 (contains my root partition)
Cannot find device with /sbin/init. Retrying.

This could be SystemRescueCD, but I guess it is the same reason why ubuntu is not booting here.

Besides that, I can manually mount /dev/sda2 in SystemRescueCD (with btrfs).

I'm getting the same behavour as Thomas Mayer with the 16.04 mini.iso.

This is maybe related to https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1460447/comments/19 and not `btrfs` – The message may be misleading.