8. K8 Volumes

Need for Volumes

Used to persist data in K8

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Storage Requirements

1. Storage that dont depend on pod lifecycle

2. Storage must be available on all nodes

3. Storage needs to survive even if cluster crashes

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Volume Types

1. Persistent Volume

• a cluster resource

• created via YAML file

• needs actual physical storage like local disk, nfs server or cloud storage

• These volumes are not namespaced

• Local volumes violate 2 and 3 requirement for storage

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2. Persistant Volume Claims (PVC)

• Used by services to claim the created volume for use

• Claims must be in the same namespace

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ConfigMap & Secret

• Do not use PV or PVC

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3. Storage Class

• Provision Persistent Volumes Dynamically when PVC claims it

• Can be created via YAML file

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  • Storage Backend is defined in SC component

    • via provisioner attribute

    • each storage backend has own provisioner

    • internal provisioner - kubernetes.io

    • external provisioner

  • Configure parameters for storage

• Same as PV, it is claimed by PVC in the pods

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