# 8. K8 Volumes

### Need for Volumes

Used to persist data in K8

***

### 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

***

### 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
*

```
<figure><img src="https://1920086362-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDfv51K0WXLZdwTryHQZc%2Fuploads%2FPdvNLGPJ62gwzetQK0tz%2Fimage.png?alt=media&#x26;token=99ec5063-158f-4e44-b721-71eb4f27f2d1" alt=""><figcaption></figcaption></figure>
```

*

```
<figure><img src="https://1920086362-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDfv51K0WXLZdwTryHQZc%2Fuploads%2F0IxjrFm0rGnOEoAWbkUO%2Fimage.png?alt=media&#x26;token=be36368c-1d5b-4ba0-9452-b31ace3d3dc1" alt=""><figcaption></figcaption></figure>
```

#### 2. Persistant Volume Claims (PVC)

* Used by services to claim the created volume for use
* Claims must be in the same namespace
*

```
<figure><img src="https://1920086362-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDfv51K0WXLZdwTryHQZc%2Fuploads%2F2rXuh9fGuQw9xPsTEQmc%2Fimage.png?alt=media&#x26;token=dbeef59a-fd70-46e9-ad2f-a62fac0bd6f7" alt=""><figcaption></figcaption></figure>
```

**ConfigMap & Secret**

* Do not use PV or PVC
*

```
<figure><img src="https://1920086362-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDfv51K0WXLZdwTryHQZc%2Fuploads%2Fapj7o9IRGVR4Zlsq8Y7n%2Fimage.png?alt=media&#x26;token=abeacc63-1efe-4048-879a-e7df60af719c" alt=""><figcaption></figcaption></figure>
```

#### 3. Storage Class

* Provision Persistent Volumes Dynamically when PVC claims it
* Can be created via YAML file
  \*

  ```
  <figure><img src="https://1920086362-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDfv51K0WXLZdwTryHQZc%2Fuploads%2FE3GiOEjlCipVj7i2N7gp%2Fimage.png?alt=media&#x26;token=56efa63b-babf-44bd-8ab3-85682cce44ec" alt=""><figcaption></figcaption></figure>
  ```

  * 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
  \*

  ```
  <figure><img src="https://1920086362-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDfv51K0WXLZdwTryHQZc%2Fuploads%2FDAt1hwTQAcG7N21vHpLn%2Fimage.png?alt=media&#x26;token=f9f5b9f1-113b-46a2-893e-ae21af0f85f5" alt=""><figcaption></figcaption></figure>
  ```

***


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