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Storage Classes: Different Storage Types

Storage Classes are like different storage types. Fast storage. Slow storage. Expensive. Cheap. That's Storage Classes.

🎯 The Big Picture​

Think of Storage Classes like different storage types in hotel. Fast storage (SSD). Slow storage (HDD). Expensive (premium). Cheap (standard). That's Storage Classes.

Storage Classes define storage types. Different performance. Different cost. Dynamic provisioning. Essential for storage management.

The Storage Type Analogy​

Think of Storage Classes like storage types:

fast-ssd: Premium storage

  • Fast
  • Expensive
  • High performance

standard: Standard storage

  • Medium speed
  • Medium cost
  • Standard performance

slow-hdd: Budget storage

  • Slow
  • Cheap
  • Low performance

Once you see it this way, Storage Classes make perfect sense.

What is a Storage Class?​

StorageClass definition:

  • Defines storage type
  • Provisioner
  • Parameters
  • Dynamic provisioning

Think of it as: Storage type definition. Performance. Cost. Provisioner.

Why Storage Classes?​

Problems without Storage Classes:

  • Manual PV creation
  • No dynamic provisioning
  • Limited flexibility
  • Admin overhead

Solutions with Storage Classes:

  • Dynamic provisioning
  • Automatic PV creation
  • Flexible
  • Less admin work

Real example: I once created PVs manually. Every request. Manual work. With Storage Classes, automatic. Never going back.

Storage Classes aren't optional. They're essential.

Storage Class Structure​

Basic Storage Class:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp3
  fsType: ext4

What this does:

  • Defines storage type
  • AWS EBS provisioner
  • gp3 volume type
  • ext4 filesystem

Think of it as: Storage type. AWS. Fast. Standard.

Common Storage Classes​

AWS EBS​

AWS storage:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: aws-gp3
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  fsType: ext4
  encrypted: "true"
volumeBindingMode: WaitForFirstConsumer

Why:

  • AWS integration
  • gp3 volumes
  • Encrypted
  • Production-ready

Azure Disk​

Azure storage:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: azure-ssd
provisioner: disk.csi.azure.com
parameters:
  skuName: Premium_LRS
  fsType: ext4

Why:

  • Azure integration
  • Premium storage
  • Production-ready

GCP Persistent Disk​

GCP storage:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gcp-ssd
provisioner: pd.csi.storage.gke.io
parameters:
  type: pd-ssd
  replication-type: regional-pd

Why:

  • GCP integration
  • SSD storage
  • Regional replication

Volume Binding Modes​

Binding behavior:

Immediate:

  • Bind immediately
  • PV created when PVC created
  • Before pod scheduling

WaitForFirstConsumer:

  • Wait for pod
  • PV created when pod scheduled
  • Topology aware

Example:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: kubernetes.io/aws-ebs
volumeBindingMode: WaitForFirstConsumer

Think of it as: When to create storage. Immediately or wait.

Reclaim Policy​

What happens when PVC deleted:

Retain:

  • Keep PV
  • Manual cleanup
  • Data preserved

Delete:

  • Delete PV
  • Automatic cleanup
  • Data deleted

Recycle (deprecated):

  • Reuse PV
  • Old behavior
  • Not recommended

Example:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: kubernetes.io/aws-ebs
reclaimPolicy: Retain

Think of it as: What happens to storage. Keep or delete.

Real-World Example: Complete Storage Class​

Production-ready Storage Class:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: production-ssd
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  iops: "3000"
  throughput: "125"
  fsType: ext4
  encrypted: "true"
  kmsKeyId: "arn:aws:kms:..."
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Retain
allowVolumeExpansion: true

What this provides:

  • Fast SSD storage
  • Encrypted
  • High IOPS
  • Expandable
  • Production-ready

That's a complete Storage Class. Production-ready.

My Take: Storage Class Strategy​

Here's what I do:

Development:

  • Use standard storage
  • Cost-effective
  • Basic performance

Production:

  • Use fast storage
  • High performance
  • Encrypted
  • Expandable

The key: Use appropriate storage class. Fast for production. Standard for dev. Right tool.

Memory Tip: The Storage Type Analogy​

Storage Classes = Storage types

fast-ssd: Premium standard: Standard slow-hdd: Budget Binding mode: When to create

Once you see it this way, Storage Classes make perfect sense.

Common Mistakes​

  1. Not setting default: Manual specification needed
  2. Wrong provisioner: Doesn't work
  3. Not understanding binding: Confusion
  4. Wrong reclaim policy: Data loss or waste
  5. Not encrypting: Security risk

Key Takeaways​

  1. Storage Classes define storage types - Performance, cost
  2. Enable dynamic provisioning - Automatic PV creation
  3. Binding modes matter - Immediate or wait
  4. Reclaim policy matters - Retain or delete
  5. Use appropriate class - Fast for production

What's Next?​

Now that you understand Storage Classes, let's learn about using Persistent Volumes. Next: Using Persistent Volumes.

Remember: Storage Classes are like storage types. Fast. Slow. Expensive. Cheap. Enable dynamic provisioning. Use appropriate class. Right tool for job.