What is the Copy-on-Write (CoW) strategy used by Docker’s storage drivers and how does it affect performance?

Question

Docker Fundamentals — Hard

What is the Copy-on-Write (CoW) strategy used by Docker’s storage drivers and how does it affect performance?

Accepted Answer

Copy-on-Write (CoW) in Docker ensures that image layers are shared and read-only, minimizing storage usage. When a container modifies a file, only that specific file is copied to the container's writable layer, reducing duplication but adding overhead for initial writes.