On 2021/10/19 11:54, Emil Heimpel wrote:

Hi all,

One of my drives of a raid 5 btrfs array failed (was dead completely) so I installed an identical replacement drive. The dead drive was devid 1 and the new drive /dev/sde. I used the following to replace the missing drive:

sudo btrfs replace start -B 1 /dev/sde1 /mnt/btrfsrepair/

and it completed successfully without any reported errors (took around 2 weeks though...).

I then tried to see my array with filesystem show, but it hung (or took longer than I wanted to wait), so I did a reboot.

Any dmesg of that time?

It showed up after a reboot as followed:

Label: 'BlueButter'  uuid: 7e3378e6-da46-4a60-b9b8-1bcc306986e3
         Total devices 6 FS bytes used 20.96TiB
         devid    0 size 7.28TiB used 5.46TiB path /dev/sde1
         devid    2 size 7.28TiB used 5.46TiB path /dev/sdb1
         devid    3 size 2.73TiB used 2.73TiB path /dev/sdg1
         devid    4 size 2.73TiB used 2.73TiB path /dev/sdd1
         devid    5 size 7.28TiB used 4.81TiB path /dev/sdf1
         devid    6 size 7.28TiB used 5.33TiB path /dev/sdc1

I then tried to mount it, but it failed, so I run a readonly check and it reported the following problem:

And dmesg for the failed mount?

Thanks,
Qu

[...]
[2/7] checking extents
ERROR: super total bytes 38007432437760 smaller than real device(s) size 46008994590720
ERROR: mounting this fs may fail for newer kernels
ERROR: this can be fixed by 'btrfs rescue fix-device-size'
[3/7] checking free space tree
[...]

So I followed that advice but got the following error:

sudo btrfs rescue fix-device-size /dev/sde1
ERROR: devid 1 is missing or not writeable
ERROR: fixing device size needs all device(s) to be present and writeable

So it seems something went wrong or didn't complete fully.
What can I do to fix this problem?

uname -a
Linux BlueQ 5.14.12-arch1-1 #1 SMP PREEMPT Wed, 13 Oct 2021 16:58:16 +0000 x86_64 GNU/Linux

btrfs --version
btrfs-progs v5.14.2

Regards,
Emil

P.S.: Yes, I know, raid5 isn't stable but it works good enough for me ;)
Metadata is raid1 btw...