Kubernetes Series - Part 4: Storage and Persistence • Astro Theme Cactus

Part 1: Core Fundamentals
Part 2: Workload Management
Part 3: Networking Essentials
Part 4: Storage and Persistence (Current)
Part 5: Configuration and Secrets
Part 6: Security and Access Control
Part 7: Observability
Part 8: Advanced Patterns
Part 9: Production Best Practices

Introduction

After managing stateful applications in Kubernetes for several years, I’ve learned that proper storage configuration is crucial for data reliability and performance. In this article, I’ll share practical insights from real-world experience managing persistent storage in production environments.

Persistent Volumes

Here’s a production-ready PV configuration we use with cloud providers:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: data-volume
  labels:
    type: ssd
    environment: production
spec:
  capacity:
    storage: 100Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: fast-ssd
  csi:
    driver: ebs.csi.aws.com
    volumeHandle: vol-0123456789abcdef0
    fsType: ext4
    volumeAttributes:
      encrypted: "true"

Storage Classes

We use different storage classes for different needs:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  iopsPerGB: "3000"
  encrypted: "true"
reclaimPolicy: Retain
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

PV Best Practices

Volume Types
- Use SSD for performance-critical workloads
- Consider cost vs performance
- Implement proper encryption
Reclaim Policies
- Use Retain for important data
- Implement backup strategies
- Plan for disaster recovery

Persistent Volume Claims

Here’s how we request storage in our applications:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: database-data
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: fast-ssd
  resources:
    requests:
      storage: 100Gi
  selector:
    matchLabels:
      type: ssd
      environment: production

PVC Tips from Production

Sizing Considerations
- Start with conservative estimates
- Monitor usage patterns
- Plan for growth
```
resources:
  requests:
    storage: 100Gi
  limits:
    storage: 150Gi
```
Access Modes
- Choose appropriate access mode
- Consider multi-pod access needs
- Plan for scaling

Volume Snapshots

We use this for backup and migration:

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: data-snapshot
spec:
  volumeSnapshotClassName: csi-aws-vsc
  source:
    persistentVolumeClaimName: database-data

Snapshot Best Practices

Backup Strategy
- Regular automated snapshots
- Retention policy
- Verification process
Restoration Testing
- Regular restore tests
- Document procedures
- Automate where possible

Dynamic Provisioning

Our dynamic provisioning setup:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: dynamic-ssd
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  encrypted: "true"
  kmsKeyId: arn:aws:kms:region:account:key/key-id
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

Dynamic Provisioning Tips

Storage Options
- Configure default storage class
- Set appropriate parameters
- Monitor provisioning status
Cost Management
- Set storage limits
- Monitor usage
- Implement cleanup policies

Volume Expansion

How we handle growing storage needs:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: expandable-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 100Gi
  storageClassName: expandable-storage

Expansion Considerations

Planning
- Monitor usage trends
- Set up alerts
- Plan for downtime if needed
Implementation
- Test expansion procedures
- Document steps
- Monitor for errors

Common Storage Issues

From my experience, here are frequent problems and solutions:

Performance Issues
- Monitor IOPS
- Check storage class settings
- Verify network connectivity
Capacity Problems
- Set up monitoring
- Implement alerts
- Plan for expansion
Data Loss Prevention
- Regular backups
- Snapshot strategy
- Disaster recovery plan

Production Checklist

✅ Storage Configuration

Appropriate storage classes
Backup configuration
Monitoring setup
Encryption enabled

✅ Volume Management

Snapshot schedule
Retention policy
Restore procedures
Expansion strategy

✅ Performance

IOPS monitoring
Latency tracking
Resource utilization
Alert configuration

✅ Security

Encryption at rest
Access controls
Audit logging
Compliance checks

Real-world Example

Here’s a complete example of a production database setup:

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: fast-ssd
  resources:
    requests:
      storage: 100Gi
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: postgres
spec:
  serviceName: postgres
  replicas: 1
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
      - name: postgres
        image: postgres:14
        volumeMounts:
        - name: postgres-data
          mountPath: /var/lib/postgresql/data
        resources:
          requests:
            memory: "2Gi"
            cpu: "1"
          limits:
            memory: "4Gi"
            cpu: "2"
      volumes:
      - name: postgres-data
        persistentVolumeClaim:
          claimName: postgres-data

Conclusion

Proper storage management in Kubernetes requires careful planning and ongoing maintenance. Key takeaways from my experience:

Choose appropriate storage classes
Implement proper backup strategies
Monitor performance and capacity
Plan for growth and scaling
Test disaster recovery regularly

In the next part, we’ll explore configuration and secrets management, where I’ll share practical tips for managing application configurations securely.

Kubernetes Series - Part 4: Storage and Persistence

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