Named Volumes

What is a named volume?

A named volume is a storage unit that Docker creates and manages on your behalf. Docker stores volume data under its own directory (typically /var/lib/docker/volumes/ on Linux). You refer to the volume by name — never by a host path.

Because Docker owns the storage location, named volumes:

Work identically on Linux, macOS, and Windows.
Survive docker rm — the volume is separate from the container.
Can be shared between multiple containers simultaneously.
Are the recommended way to persist application data in production.

Managing volumes

Create a volume

docker volume create mydata

List all volumes

docker volume ls

Expected output:

DRIVER    VOLUME NAME
local     mydata

Inspect a volume

docker volume inspect mydata

[
  {
    "CreatedAt": "2024-06-01T10:00:00Z",
    "Driver": "local",
    "Mountpoint": "/var/lib/docker/volumes/mydata/_data",
    "Name": "mydata",
    "Scope": "local"
  }
]

Mountpoint is where Docker stores the actual data on the host. You rarely need to access it directly — Docker abstracts it away.

Remove a volume

docker volume rm mydata

A volume cannot be removed while a container is using it. Remove the container first, or use docker volume prune to delete all unused volumes at once.

Mounting a volume into a container

There are two syntaxes. Both are equivalent — use whichever you find more readable.

Short -v syntax:

docker run -d --name myapp -v mydata:/app/data myimage

Long --mount syntax (explicit and recommended for scripts):

docker run -d --name myapp \
  --mount type=volume,source=mydata,target=/app/data \
  myimage

If the volume mydata does not exist yet, Docker creates it automatically when you run the container.

Data persists across container replacements

The key property of a named volume: you can delete the container and recreate it, and all the data written to the volume is still there.

# Run a container and write data
docker run --name writer -v mydata:/app/data alpine sh -c "echo 'persistent' > /app/data/file.txt"

# Remove the container
docker rm writer

# Start a brand-new container mounting the same volume
docker run --rm -v mydata:/app/data alpine cat /app/data/file.txt
# Output: persistent

Hands-on practice

The snippet below runs a container, writes data to a named volume, removes the container, and mounts the same volume in a new container to prove the data survived.

# 1. Create a named volume
docker volume create demo-vol

# 2. Write data into the volume via a container
docker run --rm -v demo-vol:/data alpine sh -c "echo 'data survives!' > /data/message.txt"

# 3. Read it back from a completely new container
docker run --rm -v demo-vol:/data alpine cat /data/message.txt

# 4. Inspect the volume
docker volume inspect demo-vol

# 5. Clean up
docker volume rm demo-vol