Storage

Question 1

What types of volume types are there? Describe them

Answer 1

emptyDir - empty dir in Pod with read write access, persisted only for the duration of the pod
hostPath - file or dir from hosts node filesystem
configMapSecret - Provides a way to inject configuration data
nfs - network file system share. Preserves data after pod restart
persistentVolumeClaim - claims a persistent volume resource

Question 2

What is the difference between emptyDir and hostPath?

Answer 2

emptyDir is persisted only for the duration of the pod and must be an empty directory, hostPath can be a directory or file and can already exist in the host or can be created on Pod startup

Question 3

What is the use case for emptyDir and hostPath?

Answer 3

emptyDir might be used for scratch space, cache or for an algorithm
hostPath might be used when a container needs access to docker internals or if a process running inside it needs access to the host

Question 4

How would you create a volume in a pod yaml file?

Answer 4

apiVersion: v1
kind: Pod
metadata:
name: a-pod
spec:
volumes:
- name: a-volume
emptyDir: {}
container:
- name: a-container
image: nginx
volumeMounts:
- name: a-volume
mountPath: /var/logs

Question 5

What’s the yaml file for a persistent volume?

Answer 5

apiVersion: v1
kind: PersistentVolume
metadata:
name: a-volume
spec:
capacity:
storage: 1Gi
accessModes:
- ReadWriteMany
hostPath:
path: /var/logs

Question 6

What are the configuration optons for a pv?

Answer 6

Storage capacity : 1GI e.g.
hostPath
StorageClassName
Access modes:
- ReadWriteOnce RWO
- ReadWriteMany RWX
- ReadOnlyOnce ROX
- ReadWriteOncePod RWOP
Volume mode:
- filesystem
- block
Reclaim policy:
- Retain (Default)
- Delete

Question 7

What is the yaml file for a pvc that is statically provisioned, requires readwriteonce access and 256Mi of storage?

Answer 7

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: a-pvc
spec:
accessModes:
- ReadWriteOnce
storageClassName: “”
resources:
requests:
storage: 256Mi

Question 8

After creating a pvc what does the “Bound” status mean?

Answer 8

It means that the pvc found a pv to attatch to

Question 9

Using an yaml file, how would you attatch a pvc to a pod?

Answer 9

apiVersion: v1
kind: Pod
metadata:
name: a-pod
spec:
volumes:
- name: a-volume
persistentVolumeClaim:
claimName: a-pvc
containers:
- name: a-container
image: alpine
volumeMounts:
- name: a-volume
mountPath: /var/log

Question 10

What is a storage class?

Answer 10

A storage class is a kunernetes primitive that defines a specific type or claim of storage