Storage driver options in Docker - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Identify the storage driver used by Docker

You run the command docker info to check Docker's storage driver. Which output line correctly shows the storage driver in use?

Docker

docker info

A Storage Driver: btrfs

B Storage Driver: aufs

C Storage Driver: overlay2

D Storage Driver: devicemapper

💡 Hint

Look for the line starting with 'Storage Driver:' in the output.

The 'docker info' command shows the current storage driver under the 'Storage Driver:' line. 'overlay2' is the default and most common on modern Linux systems.

❓ Configuration

intermediate

Configure Docker to use a specific storage driver

You want Docker to use the 'devicemapper' storage driver. Which configuration file and setting correctly applies this change?

A In /etc/docker/daemon.json, set {"driver": "devicemapper"}

B In /etc/docker/daemon.conf, set storage_driver=devicemapper

C In /etc/docker/config.json, set "driver": "devicemapper"

D In /etc/docker/daemon.json, set {"storage-driver": "devicemapper"}

💡 Hint

Docker daemon configuration uses JSON format in daemon.json.

The Docker daemon reads /etc/docker/daemon.json for configuration. The correct key to set the storage driver is 'storage-driver'.

❓ Troubleshoot

advanced

Troubleshoot Docker storage driver error on startup

Docker fails to start and logs an error about the storage driver 'aufs' not being supported. What is the most likely cause?

A The Linux kernel does not have aufs support enabled or installed

B The Docker daemon configuration file is missing

C The Docker client version is incompatible with the daemon

D The Docker image is corrupted

💡 Hint

Storage drivers depend on kernel modules.

The 'aufs' driver requires kernel support. If the kernel lacks aufs modules, Docker cannot use it and will fail to start with that error.

✅ Best Practice

advanced

Choose the best storage driver for production Docker on modern Linux

Which storage driver is recommended for most production Docker setups on modern Linux distributions?

A overlay2

B aufs

C devicemapper

D btrfs

💡 Hint

Consider stability, performance, and kernel support.

Overlay2 is the default and recommended driver for modern Linux kernels due to its performance and stability.

🧠 Conceptual

expert

Understand the impact of changing Docker storage driver

What happens to existing Docker images and containers if you change the storage driver in Docker's configuration and restart the daemon?

A Docker deletes all images and containers but keeps volumes intact

B Existing images and containers become inaccessible because storage formats differ

C Docker automatically converts all images and containers to the new storage driver format

D Nothing changes; images and containers remain usable without interruption

💡 Hint

Storage drivers use different ways to store data on disk.

Changing the storage driver changes how Docker stores images and containers. Existing data is not compatible and becomes inaccessible.