Package: util-linux
Version: 2.33.1-0.1
lsblk --version: lsblk from util-linux 2.33.1
Kernel: 4.19.0-14-cloud-amd64
Debian: 10.8
With BTRFS filesystems with multiple devices (e.g. a single topology of
a filesystem consisting 2 devices) lsblk does not populate the
MOUNTPOINT field (as it does for LVM multiple device filesystems). This
can cause confusion (lsblk tends to be one of the most important
commands to examine a system's block device topology). While on the more
traditional LVM stack one gets the mount point, for the newer btrfs we
don't get the same information.
Example on a system with a multi device btrfs filesystem
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
...
vdb 254:16 0 2T 0 disk
└─vdb1 254:17 0 2T 0 part /data
vdc 254:32 0 2T 0 disk
└─vdc1 254:33 0 2T 0 part
# lsblk -f
vdb
└─vdb1 btrfs be86d428-b3f2-4fb7-ac07-a4b41f92a4ac 2,1T 47% /data
vdc
└─vdc1 btrfs be86d428-b3f2-4fb7-ac07-a4b41f92a4ac
while examining btrfs commands we can see the relationship
# btrfs device usage /data
/dev/vdb1, ID: 1
Device size: 2.00TiB
...
/dev/vdc1, ID: 2
Device size: 2.00TiB
...
For comparison here is a listing from another system (also debian 10.8
and same lsblk version) with LVM formatted filesystem
# lsblk
vdb 254:16 0 2T 0 disk
└─vdb1 254:17 0 2T 0 part
└─vg-data 253:0 0 3T 0 lvm /data
vdc 254:32 0 2T 0 disk
└─vdc1 254:33 0 2T 0 part
└─vg-data 253:0 0 3T 0 lvm /data
Kind Regards
V.G.
