https://docs.docker.com/engine/tutorials/dockervolumes/

Data volumes are designed to persist data, independent of the container’s life cycle. Docker therefore never automatically delete volumes when you remove a container, nor will it “garbage collect”     volumes that are no longer referenced by a container.
A Docker data volume persists after a container is deleted.

Volumes types:

• Anonymous Volume: any volume without a source, docker will create this as a local volume with a long unique id, and it behaves as a named volume
• Named Volume - local storage (original image data located in specified directory are copied to volume during creation)
  • local driver is using /var/lib/docker/volumes for storage
  • original image data is copied if volume is empty.
  • All UID/GIDs are correctly set
  • user has to take care about free space at /var/lib/docker/volumes
• Host volume: bind-mounted host
  • original image data are not copied
  • fastest - no volume driver is used
  • possible problem with UID/GID permisions
  • volume can be created on any location (different discs, etc)
• volume plugins

Move volume between discs:

rsync -aqxP jenkins1_jenkins_homeSNAP/ /mnt/NVMe/@jenkins1_jenkins_home

Sometimes 3rd party script or compose depends on named volumes, but we want to put particular named volume on different (faster) drive.

from cmdline:

docker volume create -d local -o type=none -o o=bind -o device=/mnt/ssd/pgsql pgsql-data

od compose file:

volumes:
  pgsql-data:
    driver: local
    driver_opts:
      type: none
      o: bind
      device: /mnt/ssd/pgsql

https://github.com/anybox/buttervolume

Volume destination inside container must be a absolute path.

Run shell with mounted volume from another docker:

docker run --rm -i --volumes-from dbdata busybox ash

docker run --rm -i --volumes-from dbdata debian:jessie-slim /bin/bash

Single file can be mounted as volume:

docker run --rm -it -v ~/.bash_history:/root/.bash_history debian:jessie-slim bash /bin/bash

Create named volume and share it between multiple containers:

docker run -d -P -v my-named-volume:/opt --name test1 debian:jessie-slim bash
docker run -d -P -v my-named-volume:/opt --name test2 debian:jessie-slim bash
docker run -d -P -v my-named-volume:/opt --name test3 debian:jessie-slim bash

To protect data from being deleted with volume use local-persist plugin: https://github.com/CWSpear/local-persist

Find orphaned volumes

docker volume ls -f dangling=true
docker volume rm <volume name>

Transfer volume to another host https://www.guidodiepen.nl/2016/05/transfer-docker-data-volume-to-another-host/

https://github.com/gdiepen/docker-convenience-scripts/blob/master/docker_get_data_volume_info.sh

http://mysqlrelease.com/2016/08/trying-out-mysql-in-docker-swarm-mode/ https://forums.docker.com/t/data-base-persistence-in-docker-swarm-mode/20665/7