Memory limits and reservations in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a memory limit in Docker?

A memory limit sets the maximum amount of memory a container can use. If the container tries to use more, it may be stopped or killed.

beginner

What does memory reservation mean in Docker?

Memory reservation is the amount of memory that Docker guarantees to a container. It helps ensure the container has enough memory to run smoothly.

beginner

How do you set a memory limit when running a Docker container?

Use the option --memory followed by the limit size, for example: docker run --memory=500m myimage limits memory to 500 megabytes.

intermediate

What happens if a container exceeds its memory limit?

Docker may stop or kill the container to prevent it from using more memory than allowed, protecting the host system.

intermediate

Why use memory reservation along with memory limits?

Memory reservation ensures the container has enough memory to run well, while the limit prevents it from using too much and affecting other containers.

Which Docker option sets the maximum memory a container can use?

A --cpu-shares

B --memory

C --memory-reservation

D --memory-swap

The --memory option sets the maximum memory limit for a container.

What does --memory-reservation do in Docker?

A Guarantees a minimum memory amount

B Sets the maximum memory limit

C Limits CPU usage

D Sets disk space limit

--memory-reservation guarantees a minimum amount of memory for the container.

If a container exceeds its memory limit, what usually happens?

A It gets more memory automatically

B It slows down but keeps running

C Docker stops or kills the container

D Nothing happens

Docker stops or kills containers that exceed their memory limits to protect the host.

Which is true about memory reservation?

A It is the minimum memory guaranteed

B It sets disk quota

C It controls CPU priority

D It is the maximum memory allowed

Memory reservation guarantees a minimum amount of memory for the container.

How do you limit a container's memory to 1 gigabyte?

A docker run --memory-reservation=1g ...

B docker run --memory-swap=1g ...

C docker run --cpu-shares=1g ...

D docker run --memory=1g ...

Use --memory=1g to limit the container's memory to 1 gigabyte.

Explain the difference between memory limits and memory reservations in Docker.

Think about max vs guaranteed memory.

Describe how to set memory limits and reservations when running a Docker container.

Recall the Docker run command options.