Amazon EKS — EBS CSI Driver

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EBS CSI Driver

Amazon EBS (Elastic Block Store) provides block-level storage volumes for EC2 instances. The EBS CSI driver lets Kubernetes dynamically create and attach EBS volumes to pods.

How EBS Works with EKS

EBS CSI Driver Flow
┌────────────────────────────────────────────────────┐
│                                                    │
│  1. Pod requests PVC                               │
│  2. CSI driver calls AWS API                       │
│  3. EBS volume created in same AZ as node          │
│  4. Volume attached to EC2 instance                │
│  5. Volume mounted into pod                        │
│                                                    │
│  ┌────────┐    ┌──────────┐    ┌─────────────┐   │
│  │  Pod   │────│  Node    │────│ EBS Volume  │   │
│  │ /data  │    │ (EC2)    │    │ (gp3, 50GB) │   │
│  └────────┘    └──────────┘    └─────────────┘   │
│                                                    │
│  ⚠️ EBS is AZ-specific — volume and node must     │
│     be in the same AZ                              │
└────────────────────────────────────────────────────┘

Install EBS CSI Driver

# Method 1: EKS managed addon (recommended)
$ aws eks create-addon \
    --cluster-name demo \
    --addon-name aws-ebs-csi-driver \
    --service-account-role-arn arn:aws:iam::123456789012:role/AmazonEKS_EBS_CSI_DriverRole

# Method 2: eksctl
$ eksctl create addon --name aws-ebs-csi-driver --cluster demo \
    --service-account-role-arn arn:aws:iam::123456789012:role/AmazonEKS_EBS_CSI_DriverRole

Create a StorageClass

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

WaitForFirstConsumer ensures the volume is created in the same AZ as the pod. Without this, you get AZ mismatches.

Use EBS in a Pod

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: data-pvc
spec:
  accessModes:
    - ReadWriteOnce    # EBS is single-node only
  storageClassName: ebs-gp3
  resources:
    requests:
      storage: 20Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: app
spec:
  containers:
    - name: app
      image: nginx
      volumeMounts:
        - name: data
          mountPath: /data
  volumes:
    - name: data
      persistentVolumeClaim:
        claimName: data-pvc

EBS Volume Types

Type IOPS Throughput Cost Use Case
gp3 3,000 baseline (up to 16,000) 125 MB/s (up to 1,000) $0.08/GB/mo Default choice
gp2 3 per GB (up to 16,000) 250 MB/s $0.10/GB/mo Legacy
io2 Up to 64,000 Up to 1,000 MB/s $0.125/GB + $0.065/IOPS Databases
st1 N/A Up to 500 MB/s $0.045/GB/mo Sequential reads

Common Mistakes

Mistake Impact
Not using WaitForFirstConsumer Volume and pod in different AZs
Forgetting IAM role for CSI driver Can’t create volumes
ReadWriteMany with EBS Not supported — use EFS
Not encrypting volumes Security compliance failure

What’s Next?

Shared storage: EFS CSI Driver.

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