1. Why Do We Even Need Docker Volumes? (Explained Simply)
When you run a container, everything inside it is temporary.
Example:
docker run mysql
You add some data to MySQL… You stop the container… You start again… Everything is gone.
Why? Because containers are not meant to store permanent data. They are like temporary rooms — when removed, everything inside gets wiped.
So we need a way to store data outside the container but still allow the container to use it.
And that solution is:
👉 Docker Volumes = Safe storage for your container’s data
2. Visual Concept of a Volume (Your Style)
Imagine:
Container = Temporary apartment
Volume = Locker outside the apartment
Even if the container dies → The locker still holds your data.
Visual Diagram:
┌───────────────────────┐
│ Container (MySQL) │
│ /var/lib/mysql │
└──────────┬────────────┘
│ Volume link
┌──────────┴────────────┐
│ Docker Volume Storage │
│ (Permanent Data) │
└───────────────────────┘
3. Types of Volumes (Explained Visually)
There are 3 ways Docker stores data:
1 Anonymous Volumes
Docker creates a random volume automatically.
docker run -v /data app
Visual:
Container → volume123 (unknown name, auto-generated)
2 Named Volumes
You give the volume a name.
docker run -v mydata:/data app
Visual:
Container → mydata → stored forever
3 Bind Mounts
You connect a real folder from your computer.
docker run -v /home/user/project:/app app
Visual:
Host Folder ↔ Container Folder
Best for development.
4. Real Example — Storing MySQL Data With a Volume
Let’s run MySQL the wrong way first:
docker run -e MYSQL_ROOT_PASSWORD=pass -d mysql
If container stops → ALL data gone.
Now the correct way:
docker run -e MYSQL_ROOT_PASSWORD=pass \
-v mysqldata:/var/lib/mysql \
-d mysql
Visual Breakdown:
mysqldata (volume)
↓
/var/lib/mysql inside container
→ MySQL saves everything in the volume
→ Even if container dies, data stays
5. Where Are Volumes Stored?
On Linux:
/var/lib/docker/volumes/<your-volume-name>/
Docker manages it. You don’t manually touch these folders.
6. Create Your Own Volume (Beginner Exercise)
Step 1: Create a volume
docker volume create demo
Step 2: Run a container and use it
docker run -v demo:/data -d busybox sh -c "echo hello > /data/hello.txt && sleep 1000"
Step 3: Inspect volume
docker volume inspect demo
You will see:
- storage path
- mount point
- driver
This is how you understand volumes practically.
7. Visual Summary (For Instant Recall)
Containers = temporary
Volumes = permanent
Use volumes for: databases, uploads, logs, anything important
Types = anonymous, named, bind mount
Volume lives even if container dies
8. When Should You Use a Volume? (Simple Rules)
✔ Use Volumes When:
- Using databases (MySQL, MongoDB, Postgres)
- Storing logs
- Storing user uploads
- Running containers in production
- Your container must survive restarts
✔ Use Bind Mounts When:
- You are developing code locally
- You want live code edits reflected inside container
Do NOT store data inside container filesystem if:
- You care about persistence
- You need real production setup
- You want portability
**9.FAQ **
Q1. Why does Docker delete my data when container stops?
Because container filesystem is temporary. Only volumes are permanent.
Q2. Are volumes faster than bind mounts?
Yes. Volumes are optimized by Docker for performance.
Q3. Can two containers share one volume?
Yes. A volume can be mounted into multiple containers at once.
Q4. Does deleting a container delete the volume?
No. Volumes stay until you delete them manually.
Q5. How do I delete a volume?
docker volume rm myvolume
Final Words
Docker volumes solve one big headache:
“Bro, my data is gone… again.”
With volumes, your data becomes safe, permanent, and separate from the container.
Containers can come and go — but your volume stays loyal like a storage vault outside the container’s house.
This is one of the biggest mindset shifts in Docker.