Hi,
I've setup a RAID1 with two disks (disk1 and disk2) and I'm testing the
btrfs replace command.
After replacing disk2 with disk3, I can only mount
(a) disk1 or disk3 (if both disk are plugged) and
(b) the original disk1 (degraded, if disk3 is unplugged).
I cannot mount the replacement disk3 if disk1 is unplugged.
> mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop3,
missing codepage or helper program, or other error.
What I expect is that both disk1 and disk3 are fully valid and working
after a replace.
Steps to reproduce:
dd if=/dev/zero of=/vdisk1 bs=1024 count=300000
losetup /dev/loop1 /vdisk1
dd if=/dev/zero of=/vdisk2 bs=1024 count=300000
losetup /dev/loop2 /vdisk2
dd if=/dev/zero of=/vdisk3 bs=1024 count=300000
# losetup /dev/loop3 /vdisk3 # don't plug this device yet
Create RAID1 file system:
mkfs.btrfs -L datavol -m raid1 -d raid1 /dev/loop1 /dev/loop2
Unplug device 2 to simulate a defect:
losetup -d /dev/loop2
Plug device 3:
losetup /dev/loop3 /vdisk3
Replace device 2 with device 3:
mount -o degraded /dev/loop1 /mnt
btrfs filesystem show # to get devid of device 2
btrfs replace start -Br 2 /dev/loop3 /mnt
btrfs replace status /mnt # check success
umount /mnt
Unplug the original device 1 to see if device 3 has really replaced
device 2:
losetup -d /dev/loop1
mount -o degraded /dev/loop3 /mnt
The mount fails with this error:
> mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop3,
missing codepage or helper program, or other error.
In this situation, btrfs device scan does not change anything and btrfs
filesystem show shows:
> warning, device 1 is missing
> warning, device 1 is missing
> warning, device 1 is missing
> warning, device 1 is missing
> bad tree block 198180864, bytenr mismatch, want=198180864, have=0
> ERROR: cannot read chunk root
> Label: 'datavol' uuid: 640e45d3-e741-4a78-a24e-2d8a41c6b8c3
> Total devices 2 FS bytes used 128.00KiB
> devid 2 size 292.97MiB used 104.00MiB path /dev/loop3
> *** Some devices missing
Is this a known problem? Can you reproduce it? Am I doing something wrong?
Regards, Jakob
