On 08/30/2018 11:35 AM, Qu Wenruo wrote:

On 2018/8/30 下午5:13, Pierre Couderc wrote:

quoted

Trying to install a RAID1 on a debian stretch, I made some mistake and
got this, after installing on disk1 and trying to add second disk  :


root@server:~# fdisk -l
Disk /dev/sda: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x2a799300

Device     Boot Start        End    Sectors  Size Id Type
/dev/sda1  *     2048 3907028991 3907026944  1.8T 83 Linux


Disk /dev/sdb: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x9770f6fa

Device     Boot Start        End    Sectors  Size Id Type
/dev/sdb1  *     2048 3907029167 3907027120  1.8T  5 Extended


And :

root@server:~# btrfs fi show
Label: none  uuid: eed65d24-6501-4991-94bd-6c3baf2af1ed
         Total devices 2 FS bytes used 1.10GiB
         devid    1 size 1.82TiB used 4.02GiB path /dev/sda1
         devid    2 size 1.00KiB used 0.00B path /dev/sdb1

...

My purpose is a simple RAID1 main fs, with bootable flag on the 2 disks
in prder to start in degraded mode....
How to get out ofr that...?

The 2nd device is indeed strange.

Considering how old packages Debian tends to deliver, it should be some
old btrfs-progs.

You could just boot into the system and execute the following commands:

# btrfs device remove 2 <mnt>

This works fine.

Then add a new real device to the fs

# btrfs device add <new device> <mnt>

Thnk you, this :

btrfs device add /dev/sdb1 /

  seems to work but  gives me the same :

root@server:~# btrfs fi show
Label: none  uuid: eed65d24-6501-4991-94bd-6c3baf2af1ed
         Total devices 2 FS bytes used 1.10GiB
         devid    1 size 1.82TiB used 4.02GiB path /dev/sda1
         devid    2 size 1.00KiB used 0.00B path /dev/sdb1

So I need to "prepare" or format /dev/sdb before adding /dev/sdb1
I have tried to format /dev/sdb and it works :
root@server:~# btrfs fi show
Label: none  uuid: eed65d24-6501-4991-94bd-6c3baf2af1ed
         Total devices 2 FS bytes used 1.10GiB
         devid    1 size 1.82TiB used 4.02GiB path /dev/sda1
         devid    2 size 1.82TiB used 0.00B path /dev/sdb

but I have no partition table and no booot flag for degraded mode....