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RAM-backed emptyDir (tmpfs)

RAM-backed emptyDir is a configuration of the Kubernetes emptyDir volume that uses the node's RAM (memory) as the storage medium, backed by a tmpfs filesystem^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md].

Configuration

This functionality is defined within the spec.volumes.emptyDir field of a Pod manifest^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md]. To enable RAM-backed storage, the medium field must be set to Memory^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md].

A sizeLimit is recommended when using this medium to constrain the amount of memory consumed^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md].

spec:
  volumes:
    - name: cache-volume
      emptyDir:
        medium: Memory
        sizeLimit: 256Mi

Characteristics

  • Performance: Because the data is stored in memory, this storage type offers very high performance^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md].
  • Capacity: The available space is limited by the system's memory resources^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md].
  • Lifetime: Like standard emptyDir, the volume's lifecycle is tied to the Pod; it is created when the Pod is started and deleted when the Pod is removed^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md].

Use Cases

Due to its high speed and volatility, this configuration is typically used to provide cache space for applications^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md].

  • [[Kubernetes Volumes]]
  • [[Pods]]
  • [[emptyDir]]

Sources

^[400-devops__06-Kubernetes__k8s-ithelp__Day17__README.md]