Re: My first attempt to use btrfs failed miserably

From: Skibbi <skibbi@gmail.com>
To: Chris Murphy <lists@colorremedies.com>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: My first attempt to use btrfs failed miserably
Date: Mon, 3 Feb 2020 07:38:49 +0100	[thread overview]
Message-ID: <CACN+yT-FrVi71HKANj7NRinyPoDG5Aowma9NT=UB2WGvqoLSVA@mail.gmail.com> (raw)
In-Reply-To: <CAJCQCtR0hzV+9S7cggGUUTtp4R1WdnSwzsOp=9fTnxvzn3Stmw@mail.gmail.com>

niedz., 2 lut 2020 o 20:56 Chris Murphy <lists@colorremedies.com> napisał(a):
>
> On Sun, Feb 2, 2020 at 5:45 AM Skibbi <skibbi@gmail.com> wrote:
>
> > root@rpi4b:~# dmesg |grep btrfs
> > [223167.290255] BTRFS: error (device dm-0) in
> > btrfs_run_delayed_refs:2935: errno=-5 IO failure
> > [223167.389690] BTRFS: error (device dm-0) in
> > btrfs_run_delayed_refs:2935: errno=-5 IO failure
> > root@rpi4b:~# dmesg |grep BTRFS
>
> The entire unfiltered dmesg is needed. This older kernel doesn't have
> new enough Btrfs tree checker code to help determine what the problem
> is.

OK, I need to reformat my drive and reproduce the issue again.

> > [203285.351377] BTRFS error (device sda1): bad tree block start, want
> > 31457280 have 0
>
> > [203285.466743] BTRFS info (device sda1): read error corrected: ino 0
> > off 32735232 (dev /dev/sda1 sector 80320)
>
> > [218811.383208] BTRFS error (device dm-0): bad tree block start, want
> > 50659328 have 7653333615399691647
>
> These happening together suggest lower storage stack failure. Since
> kernel messages are filtered it only shows that Btrfs is working as
> designed, complaining about known bad file system metadata. But
> because it's filtered, it's not clear why the metadata has gone bad.
>
> > [223167.290255] BTRFS: error (device dm-0) in
> > btrfs_run_delayed_refs:2935: errno=-5 IO failure
>
> More suggestion of IO failure, whether physical device or logical
> layer in between Btrfs and physical device. Btrfs trusts the storage
> stack *less* than other file systems, by design. It's a kind of canary
> in the coal mine. Other file systems assume the storage stack is
> working, so they're less likely to complain. Only recent versions of
> e2fsprogs will format ext4 using metadata checksumming enabled. The
> kind of problems you're reporting look so bad and happen so fast I'd
> expect a good chance you'd reproduce the same problem with any
> metadata checksumming file system, if you have new enough progs to
> enable them.

I removed luks encryption and had the same btrfs errors after several
GB of writes. Then I reformatted drive to ext4 and was able to save
60GB without hiccups. Of course, you may be right that ext4 silently
damages my data, but at least I was able to see it on the drive after
remount/reboot.
I'm beginning to think that my Pi draws more power when used with
external drive (I used only pendrives so far) so I need to investigate
for power issues.
And also I need to figure out how to get newer kernel. Raspbian is not
the freshest distro...

-- 
Best regards