Ephemeral storage, also known as container-scoped storage, is intrinsically tied to the lifecycle of a container. It exists as the container's writable layer. When a container is stopped, restarted, or deleted, this writable layer is destroyed, and any data written to it is permanently lost. This type of storage is suitable for temporary files or cache data that an application needs during its runtime but does not need to persist. The data does not survive a restart, which directly answers the question.

A. Object: Object storage is a persistent storage service external to the container. Data is managed as objects and is not lost when a container restarts.

B. Persistent volume: A persistent volume is an abstraction for a piece of storage that exists independently of a container's or pod's lifecycle, explicitly designed to preserve data.

D. Block: Block storage provides persistent volumes that can be attached to containers. The data on these volumes is independent of the container's lifecycle and survives restarts.

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1. Kubernetes Documentation

"Volumes". The official Kubernetes documentation describes ephemeral volume types like emptyDir. It states

"When a Pod is removed from a node for any reason

the data in the emptyDir is deleted forever." This confirms that data in this type of volume is lost when the container's pod is terminated. (Source: Kubernetes.io

Concepts > Storage > Volumes

Section: emptyDir).

2. Docker Documentation

"Manage data in Docker". The official Docker documentation explains that data not stored in a volume is written to the container's writable layer. It clarifies

"The data doesn't persist when that container is no longer running

and it can be difficult to get the data out of the container if another process needs it." (Source: Docker Docs

Storage > Volumes > "Manage data in Docker").

3. Red Hat Official Documentation

"Understanding container storage". This vendor documentation distinguishes between ephemeral and persistent storage. For ephemeral storage

it notes

"The storage is tightly coupled with the container’s life cycle. If the container crashes or is stopped

the storage is lost." (Source: Red Hat Customer Portal

OpenShift Container Platform 4.10 > Storage > "Understanding container storage"

Section: "Ephemeral storage").

4. University of California

Berkeley

"CS 162: Operating Systems and System Programming"

Lecture 19: "Virtual Machines

Containers

and Cloud Computing". Course materials often describe the container file system as a series of read-only layers with a final writable layer for the specific container. This top writable layer is ephemeral and is discarded when the container is destroyed. (Reference concept covered in typical advanced OS/Cloud Computing university curricula).