Hi,
I have a problem with the current BTRFS 4.6
I'm running a Archlinux in a KVM to test BTRFS.
First I played with one device and subvolumes.
After that I added a second device to make a raid1.
# btrfs device add /dev/sdb /mnt
# btrfs balance start -dconvert=raid1 -mconvert=raid1 /mnt
To make a stresstest I removed the first device and wanted to
boot, but unfortunately the system couldn't boot.
So I booted into a liveSystem:
#uname -a
Linux archiso 4.6.3-1-ARCH #1 SMP PREEMPT Fri Jun 24 21:19:13 CEST 2016
x86_64 GNU/Linux
First I tried to mount the "leftover" device with the degraded option
# mount -o degraded /dev/sda /mnt
mount: wrong fs type, bad option, bad superblock on /dev/sda,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so.
but this works only if I also use the read-only option.
# mount -oro,degraded /dev/sda /mnt
If I try then to replace the missing device I got an error
# btrfs replace start -B 1 /dev/sdb /mnt
ERROR: ioctl(DEV_REPLACE_START) failed on "/mnt": Read-only file system
Hire are some additional info about the system
# btrfs --version
btrfs-progs v4.6
# btrfs fi show
Label: 'hdd0' uuid: 97b5c51a-65d3-4a84-9382-9b99756ca4ab
Total devices 2 FS bytes used 1.09GiB
devid 2 size 10.00GiB used 3.56GiB path /dev/sda
*** Some devices missing
# btrfs fi df /mnt
Data, RAID1: total=2.00GiB, used=1.04GiB
Data, single: total=1.00GiB, used=640.00KiB
System, RAID1: total=32.00MiB, used=16.00KiB
System, single: total=32.00MiB, used=0.00B
Metadata, RAID1: total=256.00MiB, used=54.02MiB
Metadata, single: total=256.00MiB, used=256.00KiB
GlobalReserve, single: total=32.00MiB, used=0.00B
# dmesg
[ 9753.746858] BTRFS info (device sda): allowing degraded mounts
[ 9753.746863] BTRFS info (device sda): disk space caching is enabled
[ 9753.746865] BTRFS: has skinny extents
[ 9753.819035] BTRFS: missing devices(1) exceeds the limit(0), writeable
mount is not allowed
[ 9753.838758] BTRFS: open_ctree failed
[ 9800.077556] BTRFS info (device sda): allowing degraded mounts
[ 9800.077561] BTRFS info (device sda): disk space caching is enabled
[ 9800.077562] BTRFS: has skinny extents
Is this a mistake I'm doing or is this some how a bug?
Kind Regards
Tamas Baumgartner-Kis
--
Tamás Baumgartner-Kis
Rechenzentrum der Universität Freiburg
Phone: +49 761 203 4605
E-Mail: Tamas.Baumgartner-Kis@xxxxxxxxxxxxxxxxxx
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