Fixing raid1 boot

Fixing raid1 boot

[Jari Seppälä]

I have av machine which has btrfs raid1 root which I cannot boot
anymore. The problem seems to be related to "verify_parent_transid"
messages already discussed on this mailing list. However, there is no
actual help yet available to my case.

Disks
/dev/sda1 and /dev/sdb1 as /boot, 100Mb, ext3, manually mirrored
/dev/sda6 and /dev/sda6 as /, 50Gb, btrfs raid1
/dev/sda7 and /dev/sdb7 as /mnt/share, 543Gb, btrfs raid1

Boot fails and starts to loop with errors "parent transid verify failed=
 on".

However, I was able to boot from usb stick and mount the partitions wit=
h
"mount UUID=3D... <mount point> -o degraded". After unmounting the UUID
identified partitions I was also able to mount them without the "-o
degraded". Also btrfs-show shows raid devices as _not_degraded_. The
initrd+vmlinuz in use have been able to boot the / and /mnt/share befor=
e
but one boot caused by power failure corrupted something. I also can
mount /dev/sd[ab][67] directly but

I tried to use "btrfs-vol -r /dev/sd[ab][67]" with various combinations
without any luck.

btrfsck /dev/sda6 or /dev/sdb6 gives
 leaf parent key incorrect <number>
 bad block <number>

btrfsck /dev/sda7 or /dev/sdb7 gives no errors.

Any help on how to fix this boot appreciated. Especially

* How can I be sure that raid1 mirror is ok?
* Is there a way to fix any fs errors? Btrfsck does not fix just
  reports?

And yes, I know btrfs is experimental but I decided to try it anyway. I=
t
worked nicely for a week and only two problems are this recovery from
failures and hacking mkinitrd to run "btrfs device scan" which enables
boot from btrfs raid1 root partition.

Jari
--=20
*** Jari Sepp=C3=A4l=C3=A4
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