Re: RAID0 wrong (raw) device?

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

First of all there is a known issue in handling multiple paths /
instances of the same device image in btrfs. Fixing this caused
regression earlier. And my survey
    [survey]  BTRFS_IOC_DEVICES_READY return status
almost told me not to fix the bug.

But these are just a reporting issue which would confuse users, should 
be fixed.


> There is now a new behaviour: after the btrfs mount, I can see shortly the
> wrong raw device /dev/sde and a few seconds later there is the correct
> /dev/drbd3 :

yep possible. but it does not mean that btrfs kernel is using the new 
path its just a reporting (bug).



(pls use -m option)
>
> root@toy02:/etc# umount /data
> root@toy02:/etc# mount /data
> root@toy02:/etc# btrfs filesystem show
> Label: data  uuid: 411af13f-6cae-4f03-99dc-5941acb3135b
>          Total devices 2 FS bytes used 109.56GiB
>          devid    3 size 1.82TiB used 63.03GiB path /dev/drbd2
>          devid    4 size 1.82TiB used 63.03GiB path /dev/sde
>
> Btrfs v3.12
> root@toy02:/etc# btrfs filesystem show
> Label: data  uuid: 411af13f-6cae-4f03-99dc-5941acb3135b
>          Total devices 2 FS bytes used 109.56GiB
>          devid    3 size 1.82TiB used 63.03GiB path /dev/drbd2
>          devid    4 size 1.82TiB used 63.03GiB path /dev/drbd3
>
> Btrfs v3.12
>
> root@toy02:/etc# btrfs filesystem show -m
> Label: data  uuid: 411af13f-6cae-4f03-99dc-5941acb3135b
>          Total devices 2 FS bytes used 109.56GiB
>          devid    3 size 1.82TiB used 63.03GiB path /dev/drbd2
>          devid    4 size 1.82TiB used 63.03GiB path /dev/drbd3
>
> Btrfs v3.12
>



> Still, the kernel sees 3 instead of (really) 2 HGST drives:
>
> root@toy02:/etc# hdparm -I /dev/sdb | grep Number:
>          Model Number:       HGST HUS724020ALA640
>          Serial Number:      PN2134P5G2P2AX
>
> root@toy02:/etc# hdparm -I /dev/sde | grep Number:
>          Model Number:       HGST HUS724020ALA640
>          Serial Number:      PN2134P5G2P2AX

This is important to know but not a btrfs issue. Do you have multiple 
host paths reaching this this device with serial # PN2134P5G2P2AX ?