I have 2 identical servers with 2 x 2 Hitachi (HGST) SATA disks (and some
other disks) which are mirrored with drbd.
On top of this drbd setup I have created a btrfs RAID0 filesystem.
The problem now is, that btrfs shows the raw device instead of the drbd
device.
root@toy02:~# mkfs.btrfs /dev/drbd2 /dev/drbd3
root@toy02:~# mount btrfs filesystem label /dev/drbd2 data
root@toy02:~# mount /dev/drbd2 /data
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 !
root@toy02:~# uname -a; lsb_release -a
Linux toy02 3.13.0-61-generic #100-Ubuntu SMP Wed Jul 29 11:21:34 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04.3 LTS
Release: 14.04
Codename: trusty
root@toy02:~# find /dev -ls | grep drbd
47453 0 brw-rw---- 1 root disk Aug 12 14:51 /dev/drbd3
47433 0 brw-rw---- 1 root disk Aug 11 14:00 /dev/drbd2
14706 0 drwxr-xr-x 4 root root 80 Aug 10 14:17 /dev/drbd
14713 0 drwxr-xr-x 2 root root 100 Aug 12 13:40 /dev/drbd/by-res
41685 0 lrwxrwxrwx 1 root root 11 Aug 12 14:51 /dev/drbd/by-res/d3 -> ../../drbd3
42759 0 lrwxrwxrwx 1 root root 11 Aug 11 14:00 /dev/drbd/by-res/d2 -> ../../drbd2
14707 0 drwxr-xr-x 3 root root 60 Aug 10 14:17 /dev/drbd/by-disk
14708 0 drwxr-xr-x 3 root root 60 Aug 10 14:17 /dev/drbd/by-disk/disk
14709 0 drwxr-xr-x 2 root root 100 Aug 12 13:40 /dev/drbd/by-disk/disk/by-id
41682 0 lrwxrwxrwx 1 root root 17 Aug 12 14:51 /dev/drbd/by-disk/disk/by-id/ata-HGST_HUS724020ALA640_PN2134P5G2P2AX -> ../../../../drbd3
42756 0 lrwxrwxrwx 1 root root 17 Aug 11 14:00 /dev/drbd/by-disk/disk/by-id/ata-HGST_HUS724020ALA640_PN2134P5G2P2XX -> ../../../../drbd2
41681 0 lrwxrwxrwx 1 root root 8 Aug 12 14:51 /dev/block/147:3 -> ../drbd3
42755 0 lrwxrwxrwx 1 root root 8 Aug 11 14:00 /dev/block/147:2 -> ../drbd2
root@toy02:~# find /dev -ls | grep HGST
41682 0 lrwxrwxrwx 1 root root 17 Aug 12 14:51 /dev/drbd/by-disk/disk/by-id/ata-HGST_HUS724020ALA640_PN2134P5G2P2AX -> ../../../../drbd3
42756 0 lrwxrwxrwx 1 root root 17 Aug 11 14:00 /dev/drbd/by-disk/disk/by-id/ata-HGST_HUS724020ALA640_PN2134P5G2P2XX -> ../../../../drbd2
63889 0 lrwxrwxrwx 1 root root 9 Aug 12 13:42 /dev/disk/by-id/ata-HGST_HUS724020ALA640_PN2134P5G2P2AX -> ../../sdb
7429 0 lrwxrwxrwx 1 root root 9 Aug 10 16:45 /dev/disk/by-id/ata-HGST_HUS724020ALA640_PN2134P5G2P2XX -> ../../sdd
root@toy02:~# hdparm -I /dev/sdb| grep Number:
Model Number: HGST HUS724020ALA640
Serial Number: PN2134P5G2P2AX
root@toy02:~# hdparm -I /dev/sdd| grep Number:
Model Number: HGST HUS724020ALA640
Serial Number: PN2134P5G2P2XX
root@toy02:~# hdparm -I /dev/sde| grep Number:
Model Number: HGST HUS724020ALA640
Serial Number: PN2134P5G2P2AX
/dev/sdb and /dev/sde have the same serial number!
But there are really only 2 HGST drives in the server (and some other
seagate disks, non-relevant here).
root@toy02:~# find /dev -ls | grep sde
10391 0 brw-rw---- 1 root disk Aug 10 16:45 /dev/sde
8360 0 lrwxrwxrwx 1 root root 9 Aug 10 16:45 /dev/disk/by-path/pci-0000:08:00.0-scsi-0:1:2:0 -> ../../sde
8355 0 lrwxrwxrwx 1 root root 6 Aug 10 16:45 /dev/block/8:64 -> ../sde
root@toy02:~# find /dev -ls | grep sdb
10382 0 brw-rw---- 1 root disk Aug 12 13:42 /dev/sdb
68794 0 lrwxrwxrwx 1 root root 9 Aug 12 13:42 /dev/disk/by-uuid/411af13f-6cae-4f03-99dc-5941acb3135b -> ../../sdb
12410 0 lrwxrwxrwx 1 root root 9 Aug 12 13:42 /dev/disk/by-path/pci-0000:08:00.0-sas-0x1221000002000000-lun-0 -> ../../sdb
68791 0 lrwxrwxrwx 1 root root 9 Aug 12 13:42 /dev/disk/by-label/data -> ../../sdb
63890 0 lrwxrwxrwx 1 root root 9 Aug 12 13:42 /dev/disk/by-id/wwn-0x5000cca24ec137db -> ../../sdb
63889 0 lrwxrwxrwx 1 root root 9 Aug 12 13:42 /dev/disk/by-id/ata-HGST_HUS724020ALA640_PN2134P5G2P2AX -> ../../sdb
12403 0 lrwxrwxrwx 1 root root 6 Aug 12 13:42 /dev/block/8:16 -> ../sdb
/dev/sdb and /dev/sde are in reality the same physical disk!
--
Ullrich Horlacher Informationssysteme und Serverbetrieb
IZUS/TIK E-Mail: horlacher@xxxxxxxxxxxxxxxxxxxx
Universitaet Stuttgart Tel: ++49-711-68565868
Allmandring 30a Fax: ++49-711-682357
70550 Stuttgart (Germany) WWW: http://www.tik.uni-stuttgart.de/
REF:<20150812130758.GA26529@xxxxxxxxxxxxxxxxxxxx>
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