# docker images
REPOSITORY                      TAG                 IMAGE ID            CREATED             SIZE
alpine                          3.8                 11cd0b38bc3c        9 months ago        4.41MB
grafana/grafana                 5.1.5               6216a7d47b26        10 months ago       238MB
quay.io/prometheus/prometheus   v2.3.1              b82ef1f3aa07        10 months ago       119MB

# docker ps -a
CONTAINER ID        IMAGE                                  COMMAND                  CREATED             STATUS              PORTS                              NAMES
e7fdc76b0437        alpine:3.8                             "/alertmanager/alert�~@�"   8 days ago          Up 12 minutes       0.0.0.0:9093-9094->9093-9094/tcp   monitoring_alert_manager_1
732ce2eaace7        grafana/grafana:5.1.5                  "/run.sh"                8 days ago          Up 12 minutes       0.0.0.0:3000->3000/tcp             monitoring_grafana_1
75587d6787e4        quay.io/prometheus/prometheus:v2.3.1   "/bin/prometheus --l�~@�"   8 days ago          Up 12 minutes       0.0.0.0:9090->9090/tcp             monitoring_prometheus_1
a1d57121c8ce        alpine:3.8                             "/blackbox_exporter �~@�"   6 months ago        Up 12 minutes       0.0.0.0:9115->9115/tcp             monitoring_blackbox_exporter_1

# du -h -d 1 "/var/lib/docker/volumes/"
451M    /var/lib/docker/volumes/monitoring_prometheus
2.3M    /var/lib/docker/volumes/monitoring_grafana
4.0K    /var/lib/docker/volumes/monitoring_alertmanager
453M    /var/lib/docker/volumes/

# btrfs fi df /
Data, single: total=13.01GiB, used=10.82GiB
System, DUP: total=32.00MiB, used=16.00KiB
Metadata, DUP: total=639.75MiB, used=101.23MiB
GlobalReserve, single: total=16.00MiB, used=0.00B

# du -sh /
du: cannot access '/proc/1209/task/1209/fd/4': No such file or directory
du: cannot access '/proc/1209/task/1209/fdinfo/4': No such file or directory
du: cannot access '/proc/1209/fd/3': No such file or directory
du: cannot access '/proc/1209/fdinfo/3': No such file or directory
4.8G    /

# btrfs-du /
Subvolume                                                         Total  Exclusive  ID
var/lib/docker/btrfs/subvolumes/2fddeb2724f7b7ebd816c313e67580b71f36a07386bdb126e3b269cd25d40081    1.20MiB   64.00KiB  259
var/lib/docker/btrfs/subvolumes/5652e05094bbf4b171053cc6be6626d922405f699d79be265f8487b8ce3fd643    3.93MiB  784.00KiB  260
var/lib/docker/btrfs/subvolumes/c9b5313b82c7aa1e562e681e5c3344ac770e2e69820ee6bdbe9b14bf654e472f   71.81MiB  784.00KiB  261
var/lib/docker/btrfs/subvolumes/cf656f2dd19233625e66974ca89fd295583526daf4614e3f738458f629aaf8b6  114.72MiB  784.00KiB  262
var/lib/docker/btrfs/subvolumes/93a4c2f43dc245d01715a9b3c46f268f319e2d6dba2c56a7ad6078c1a98775d9  114.74MiB  784.00KiB  263
var/lib/docker/btrfs/subvolumes/5237ab02149b30f6b45de51cee89a9bec76cdc26b2e40d3cd2e37a88b331fbae  114.76MiB  800.00KiB  264
var/lib/docker/btrfs/subvolumes/6726bf1b2712fb2ed11db8629c339fd0f0afad55a9655a5e3d6ae7ca809e4c62  114.79MiB  800.00KiB  265
var/lib/docker/btrfs/subvolumes/b4eed058bca3d31d9f118b5db82515a3aa6dabcff0fb7d564e2bda1462459ce9  114.79MiB  800.00KiB  266
var/lib/docker/btrfs/subvolumes/76a59d8518448c251436254b0f7c206f65d3ccc56e3e45d1ed571c0d9377618d  114.79MiB  800.00KiB  267
var/lib/docker/btrfs/subvolumes/c740a1bfe14870a61e7fe26da24f0279a1df1d658bcfa4cf537d355f3e7c0c83   57.26MiB    3.64MiB  268
var/lib/docker/btrfs/subvolumes/23c7fccc98ddc4aa5fa1c14f54ae26efcd667e3f7a57fdf4b0870369c85861f4  232.76MiB    3.14MiB  269
var/lib/docker/btrfs/subvolumes/fe33b8bde93cb411035756fa901091261201b86260501035084db889f3e353f4  232.78MiB    3.14MiB  270
var/lib/docker/btrfs/subvolumes/300d2b8c2dfcbbccd09d3cae14d0d80618f5ccd2b53ddacab110057bc4cf9c4f    4.47MiB  160.00KiB  322
var/lib/docker/btrfs/subvolumes/7b5e78985035cc9b7e9c5acdda898cfa661dc0aa85809aa9a2fa437df43a38f9-init    4.47MiB  160.00KiB  509
var/lib/docker/btrfs/subvolumes/7b5e78985035cc9b7e9c5acdda898cfa661dc0aa85809aa9a2fa437df43a38f9    4.47MiB  160.00KiB  510
var/lib/docker/btrfs/subvolumes/2f34bf0d5958d5d156970742d13859f82ec5990fb4e610e1155b95fb1483f3b5-init  114.79MiB  800.00KiB  699
var/lib/docker/btrfs/subvolumes/2f34bf0d5958d5d156970742d13859f82ec5990fb4e610e1155b95fb1483f3b5  114.79MiB  800.00KiB  700
var/lib/docker/btrfs/subvolumes/e202293240ca4a4c1f6b996be9ba2d044d4b3007df0c7e5a29a32a949f49ae57-init  232.78MiB    3.14MiB  701
var/lib/docker/btrfs/subvolumes/e202293240ca4a4c1f6b996be9ba2d044d4b3007df0c7e5a29a32a949f49ae57  232.78MiB    3.76MiB  702
var/lib/docker/btrfs/subvolumes/ffb1461bb86799876e58e4213483e3da2b1ffee401e975087e296015d6591972-init    4.47MiB  160.00KiB  703
var/lib/docker/btrfs/subvolumes/ffb1461bb86799876e58e4213483e3da2b1ffee401e975087e296015d6591972    4.47MiB  160.00KiB  704
Total exclusive data                                                           25.42MiB

# btrfs quota rescan /
quota rescan started
# btrfs qgroup show /
qgroupid         rfer         excl
--------         ----         ----
0/5          10.80GiB     10.80GiB
0/259         1.21MiB     64.00KiB
0/260         3.94MiB    784.00KiB
0/261        71.81MiB    784.00KiB
0/262       114.73MiB    784.00KiB
0/263       114.74MiB    784.00KiB
0/264       114.77MiB    800.00KiB
0/265       114.79MiB    800.00KiB
0/266       114.79MiB    800.00KiB
0/267       114.79MiB    800.00KiB
0/268        57.27MiB      3.64MiB
0/269       232.77MiB      3.14MiB
0/270       232.79MiB      3.14MiB
0/322         4.47MiB    160.00KiB
0/509         4.47MiB    160.00KiB
0/510         4.47MiB    160.00KiB
0/699       114.79MiB    800.00KiB
0/700       114.79MiB    800.00KiB
0/701       232.79MiB      3.14MiB
0/702       232.79MiB      3.77MiB
0/703         4.47MiB    160.00KiB
0/704         4.47MiB    160.00KiB