Re: RAID0 wrong (raw) device?

[Anand Jain <anand.jain@oracle.com>]

On 08/13/2015 10:55 PM, Ulli Horlacher wrote:
> On Thu 2015-08-13 (14:02), Ulli Horlacher wrote:
>> On Thu 2015-08-13 (15:34), anand jain wrote:
>>
>>>> root@toy02:~# df -T /data
>>>> Filesystem     Type   1K-blocks      Used  Available Use% Mounted on
>>>> /dev/sdb       btrfs 3906909856 140031696 3765056176   4% /data
>>>>
>>>> root@toy02:~# btrfs filesystem show /data
>>>> Label: data  uuid: 411af13f-6cae-4f03-99dc-5941acb3135b
>>>>           Total devices 2 FS bytes used 129.81GiB
>>>>           devid    3 size 1.82TiB used 67.03GiB path /dev/drbd2
>>>>           devid    4 size 1.82TiB used 67.03GiB path /dev/sdb
>>>>
>>>> Btrfs v3.12
>>>>
>>>> ==> btrfs shows the wrong (raw) device /dev/sdb instead of /dev/drbd3 !
>>>
>>> Don't be too alarmed by that, progs do a bit of user land fabrication
>>> (wrong). kernel may /may-not be using sdb. try -m option.
>>
>> It is really weird: meanwhile (without any mount change or even reboot) I
>> get:
>>
>> root@toy02:~# btrfs filesystem show
>> Label: data  uuid: 411af13f-6cae-4f03-99dc-5941acb3135b
>>          Total devices 2 FS bytes used 106.51GiB
>>          devid    3 size 1.82TiB used 82.03GiB path /dev/drbd2
>>          devid    4 size 1.82TiB used 82.03GiB path /dev/drbd3
>
> And now, after a reboot:
>
> root@toy02:~/bin# btrfs filesystem show
> Label: data  uuid: 411af13f-6cae-4f03-99dc-5941acb3135b
>          Total devices 2 FS bytes used 119.82GiB
>          devid    3 size 1.82TiB used 82.03GiB path /dev/drbd2
>          devid    4 size 1.82TiB used 82.03GiB path /dev/sde
>
> GRMPF!

pls use 'btrfs fi show -m' and just ignore no option or -d if fs is 
mounted, as -m reads from the kernel.

at mount you could assemble correct set of devices using mount -o device 
option.

Thanks, -Anand