How Longhorn Solves EKS Storage Limits Where EBS Falls Short

Amazon Elastic Kubernetes Service (EKS) is a robust platform for running containerized workloads at scale, but its default storage backend—Amazon Elastic Block Store (EBS)—has fundamental limitations that can create operational bottlenecks and availability risks. When stateful applications like databases, message queues, or file storage need to scale across multiple availability zones or recover from node failures, EBS constraints often force teams into complex workarounds that introduce downtime and operational overhead.

Why EBS Fails for Modern Kubernetes Workloads

EBS functions as a virtual hard drive attached to a single EC2 instance in a specific availability zone. While this model works for basic use cases, it lacks the flexibility and resilience required by modern cloud-native applications. Here’s where EBS hits its limits:

• Zone-bound volumes — An EBS volume created in us-east-1a cannot be used by a pod scheduled in us-east-1b, even if both zones are in the same region.
• Single-node attachment — Only one EC2 instance (and thus one pod) can mount an EBS volume at a time, making it unsuitable for ReadWriteMany workloads.
• No automatic failover — In the event of a node failure, the volume remains attached to the original instance. Recovery requires manual detachment, reattachment to a new instance, and filesystem remounting.
• Inflexible replication — EBS snapshots are stored in Amazon S3, which adds latency and complexity when restoring to new nodes.
• I/O bottlenecks — Since EBS is network-attached and tied to a single instance, it can become a performance bottleneck under high IOPS loads.
• Vendor lock-in — EBS is proprietary to AWS, making it difficult to migrate workloads to other cloud providers or on-premises environments.

These limitations are especially painful in highly available Kubernetes clusters where pods are dynamically scheduled across nodes and zones. When a pod fails over to a different node, the EBS volume it depends on may not be accessible, leading to application downtime.

Enter Longhorn: A Cloud-Native Storage Solution Built for Kubernetes

Longhorn is a distributed block storage system designed from the ground up for Kubernetes. Originally created by Rancher Labs and now an incubating project under the Cloud Native Computing Foundation (CNCF), Longhorn transforms local storage on Kubernetes nodes into a unified, resilient storage pool. Unlike traditional storage solutions that rely on external hardware or cloud-specific integrations, Longhorn runs entirely within your cluster, minimizing latency and eliminating vendor lock-in.

Longhorn’s architecture is built on three core principles:

• Decentralized control — Each volume is managed by its own controller, ensuring isolation and resilience. If one controller fails, others continue operating normally.
• Automatic replication — Volumes are replicated across multiple nodes (configurable for availability zone resilience), so if one node goes down, the data remains accessible.
• Self-healing — When a replica becomes unhealthy or unavailable, Longhorn automatically creates new replicas on healthy nodes, maintaining data durability.

Key Features That Address EBS Limitations

• Cross-zone and cross-node availability — Volumes can be accessed by pods scheduled in different availability zones, enabling true multi-AZ deployments.
• ReadWriteMany (RWX) support — Unlike EBS, Longhorn supports multiple pods reading and writing to the same volume simultaneously, ideal for shared file systems and stateful applications with multiple replicas.
• Automated failover — If a node fails, Longhorn automatically promotes replicas on other nodes, reducing recovery time from minutes to seconds.
• Portable storage — Longhorn volumes can be moved between clusters or cloud providers without reformatting or data migration.
• Cost efficiency — By using local node storage, Longhorn reduces reliance on expensive cloud block storage and minimizes data transfer costs.

Step-by-Step: Deploying Longhorn as Default Storage in EKS

Deploying Longhorn in an EKS cluster requires a few prerequisites and configuration steps. Here’s how to set it up reliably:

1. Prepare Your EKS Cluster

Before installing Longhorn, ensure your EKS cluster meets the requirements:

• Kubernetes version 1.18 or higher
• Worker nodes running Linux (Amazon Linux 2, Ubuntu, or Bottlerocket)
• Sufficient local storage on each node (recommended: at least 100GB per node for production)
• Open-iSCSI installed on all worker nodes

Install open-iSCSI on each node using the appropriate package manager:

# For Amazon Linux 2 or RHEL-based systems
sudo yum install -y iscsi-initiator-utils

# For Ubuntu/Debian-based systems
sudo apt-get install -y open-iscsi

Verify the service is running:

sudo systemctl enable --now iscsid
sudo systemctl status iscsid

2. Install Longhorn Using Helm

Longhorn is installed using Helm, the Kubernetes package manager. Add the Longhorn repository and install the chart:

helm repo add longhorn 
helm repo update

helm install longhorn longhorn/longhorn -n longhorn-system --create-namespace

Verify the installation by checking pod status:

kubectl get pods -n longhorn-system

All pods should be in a Running state before proceeding.

3. Set Longhorn as the Default StorageClass

After installation, Longhorn becomes available as a storage class. Set it as the default to ensure new persistent volumes (PVs) use Longhorn automatically:

kubectl patch storageclass gp2 -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"false"}}}'
kubectl patch storageclass longhorn -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'

Confirm the change:

kubectl get storageclass

4. Secure Access to the Longhorn UI

Longhorn includes a management UI for monitoring volumes, replicas, and backups. To access it securely, set up an Ingress or port-forward:

kubectl port-forward svc/longhorn-frontend -n longhorn-system 8080:80

Then, open ` in your browser. The UI provides real-time insights into your storage infrastructure, including capacity, performance, and backup status.

Real-World Impact: How Teams Are Using Longhorn

Organizations using EKS for stateful workloads—especially in finance, healthcare, and e-commerce—report significant improvements after switching from EBS to Longhorn:

• Fintech companies use Longhorn for PostgreSQL and Redis clusters, achieving automatic failover across zones with zero downtime during node failures.
• E-commerce platforms leverage RWX volumes for shared application caches and logs, reducing I/O bottlenecks and simplifying log aggregation.
• Startups running high-growth databases on EKS benefit from Longhorn’s portability, enabling seamless migration between regions or cloud providers during expansion.

Teams also appreciate Longhorn’s cost predictability. By reducing reliance on EBS and leveraging local node storage, organizations cut cloud storage costs by up to 60% in some cases, while improving performance and reliability.

Looking Ahead: Is Longhorn Right for Your EKS Cluster?

For teams running stateful applications on Amazon EKS, Longhorn offers a compelling alternative to EBS—especially when multi-zone resilience, automatic failover, and RWX support are required. While EBS remains a solid choice for simple, single-zone use cases, Longhorn’s distributed architecture, self-healing capabilities, and portability make it the better fit for modern, scalable, and resilient workloads. As Kubernetes adoption grows and stateful applications proliferate, adopting a cloud-native storage solution like Longhorn could be a key differentiator in achieving operational excellence and reducing cloud costs.