📦 Docker Volumes – A2Z Storage Guide 🐳

July 20, 2025

This content originally appeared on DEV Community and was authored by Darshan Vasani

Docker Volumes – A2Z Storage Guide

What is a Docker Volume?

A Docker volume is a persistent storage mechanism managed by Docker outside the container filesystem.

Volumes survive container restarts
Volumes are managed by Docker
They’re perfect for storing databases, logs, user uploads, and config files

Real-World Analogy:

Think of a volume as a USB stick plugged into your container.

You can eject the container
The USB (volume) still has all your files

Why Use Volumes?

Benefit	Why It’s Awesome
Persistent Storage	Data stays even after container dies
Decoupled	Separate from container logic
Shared Access	Mount same volume into multiple containers
Backup Friendly	Easy to archive/export
Safe from image rebuilds	Won’t be deleted accidentally

Types of Docker Volume Mounts

Type	Syntax Example	Use Case
Named Volume	`-v my-volume:/app/data`	Default, managed by Docker
Host Bind	`-v /host/folder:/container/folder`	Use host machine’s file system
Anonymous	`-v /app/data`	Randomly named, temporary

1. Using a Named Volume

docker volume create mydata

docker run -d \
  --name db \
  -v mydata:/var/lib/mysql \
  mysql

The data is stored in:

/var/lib/docker/volumes/mydata/_data

2. Attaching Host Folders (Bind Mounts)

docker run -d \
  --name webapp \
  -v /home/user/project:/usr/src/app \
  node:alpine

Mounts a host folder directly inside the container.

Bind mounts are powerful but risk exposing sensitive host files if misused.

Differences: Volume vs Bind Mount

Feature	Volume (Docker-managed)	Bind Mount (Host folder)
Managed by Docker	Yes	No
Host portability	Portable	Host-specific
Data safety	Isolated	Depends on host path
Security	Better	Potentially risky

3. Share Volume Between Multiple Containers

Example:

docker volume create shared-data

docker run -d --name writer \
  -v shared-data:/data \
  busybox sh -c "echo hello > /data/file.txt && sleep 9999"

docker run --rm --name reader \
  -v shared-data:/data \
  busybox cat /data/file.txt

Both writer and reader share the same volume.

Read-only Volume Mount

Prevent writing:

-v mydata:/app/data:ro

Makes volume read-only inside the container!

Volume Lifecycle Commands

Command	What It Does
`docker volume create <name>`	Create a volume
`docker volume ls`	List all volumes
`docker volume inspect <name>`	View volume details
`docker volume rm <name>`	Delete volume
`docker volume prune`	Delete all unused volumes

Using Volumes in `docker-compose.yml`

version: "3.9"
services:
  db:
    image: postgres
    volumes:
      - pgdata:/var/lib/postgresql/data

volumes:
  pgdata:

Docker creates & manages the pgdata volume

Volume Naming Tip

Named volumes persist and can be reused by name
Anonymous volumes are created automatically and can be hard to track

docker run -v /data nginx    # Anonymous volume
docker run -v myvol:/data nginx  # Named volume ✅

Backing Up & Restoring Volumes

Backup:

docker run --rm \
  -v myvolume:/data \
  -v $(pwd):/backup \
  busybox tar czvf /backup/backup.tar.gz /data

Restore:

docker run --rm \
  -v myvolume:/data \
  -v $(pwd):/backup \
  busybox tar xzvf /backup/backup.tar.gz -C /

Volume Gotchas to Avoid

Mistake	Problem
Not naming volumes	Hard to manage & reuse
Mixing bind mount with sensitive paths	Potential host damage
Forgetting to prune	Unused volumes pile up
Overwriting app folder with empty volume	App might not start!

Summary Table

Type	Managed	Persistent	Use Case
Named Volume	Docker		Safe default, backups
Bind Mount	Host		Mount local code
Anonymous Volume	Docker	Temporary	Quick test, not tracked

Final Takeaways

Volumes are best practice for persistent, portable storage.
Use named volumes for databases, uploads, logs.
Use bind mounts for local dev.
Share volumes to enable inter-container communication via files.
Clean up with docker volume prune.