Amazon EKS — EFS CSI Driver

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EFS CSI Driver

Amazon EFS (Elastic File System) provides shared file storage that multiple pods can read and write simultaneously, across all AZs.

EBS vs EFS

Feature EBS EFS
Access mode ReadWriteOnce (single node) ReadWriteMany (multi-node)
AZ Single AZ Multi-AZ
Performance High IOPS Moderate (burstable/provisioned)
Cost $0.08/GB/mo (gp3) $0.30/GB/mo (standard)
Use case Databases, single-pod storage Shared data, CMS, ML datasets
Fargate support ❌ No ✅ Yes

Install EFS CSI Driver

# EKS managed addon
$ aws eks create-addon \
    --cluster-name demo \
    --addon-name aws-efs-csi-driver \
    --service-account-role-arn arn:aws:iam::123456789012:role/AmazonEKS_EFS_CSI_DriverRole

Create EFS File System

# Create file system
$ aws efs create-file-system \
    --performance-mode generalPurpose \
    --throughput-mode bursting \
    --encrypted \
    --tags Key=Name,Value=eks-efs

# Create mount targets in each subnet
$ aws efs create-mount-target \
    --file-system-id fs-0abc123 \
    --subnet-id subnet-0def456 \
    --security-groups sg-0ghi789

Use EFS in Pods

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: efs-sc
provisioner: efs.csi.aws.com
parameters:
  provisioningMode: efs-ap
  fileSystemId: fs-0abc123
  directoryPerms: "700"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: shared-data
spec:
  accessModes:
    - ReadWriteMany     # Multiple pods can write!
  storageClassName: efs-sc
  resources:
    requests:
      storage: 5Gi

Multiple pods can mount the same PVC:

# Pod 1 and Pod 2 both mount the same EFS volume
volumes:
  - name: shared
    persistentVolumeClaim:
      claimName: shared-data

Common Mistakes

Mistake Impact
Security group not allowing NFS (2049) Mount fails
No mount targets in node subnets Timeout on mount
Using EFS for high-IOPS workloads Poor performance (use EBS)

What’s Next?

Dynamic provisioning: Storage Classes.

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