When running applications on Amazon EKS (Elastic Kubernetes Service), one of the first architectural questions you’ll face is: Which storage solution should I use?
Picking the right storage isn’t just about saving data—it directly impacts scalability, reliability, and cost-efficiency of your workloads. AWS provides multiple storage services that integrate with Kubernetes through CSI drivers, and each serves a different purpose.
In this post, we’ll compare the three primary options — Amazon EBS, Amazon EFS, and Amazon S3 (via the Mountpoint CSI driver) — to help you choose the right fit for your workloads.
Amazon EBS (Elastic Block Store)
Amazon EBS is block-level storage attached to a specific EC2 instance or pod through the EBS CSI driver. Think of it like attaching a hard drive to your VM — it’s fast, consistent, and designed for single-pod workloads.
Best suited for:
- Relational & NoSQL Databases (PostgreSQL, MySQL, Cassandra)
- Stateful applications needing low-latency, high IOPS
- Single-instance apps requiring persistence across pod restarts
Key Characteristics:
- AZ-bound: An EBS volume lives in one Availability Zone, and pods must be scheduled in the same AZ.
- Single-pod access: Most volumes are ReadWriteOnce (RWO) — meaning one pod at a time.
- Dynamic provisioning: Kubernetes can auto-create EBS volumes using PersistentVolumeClaims.
If your workload is a database or something that needs dedicated, fast disk storage, EBS is the go-to.
Amazon EFS (Elastic File System)
Amazon EFS is a fully managed, elastic NFS storage that multiple pods can mount simultaneously — even across different Availability Zones. With the EFS CSI driver, it becomes a shared, scalable storage layer for Kubernetes workloads.
Best suited for:
- Web content management (WordPress, Drupal)
- CI/CD pipelines (shared build artifacts, code repos)
- Applications needing shared data across multiple pods
- Persistent storage with ReadWriteMany (RWX) access
Key Characteristics:
- Shared access: Thousands of pods can read/write to the same file system.
- Elastic & serverless: Automatically grows/shrinks with usage.
- Multi-AZ durability: Data is stored across multiple AZs for resilience.
If you need shared storage accessible by many pods at once, EFS is the right choice.
Amazon S3 with Mountpoint CSI Driver
Amazon S3 is object storage, but with the Mountpoint for S3 CSI driver, you can mount an S3 bucket into your pod as if it were a file system. This is great for workloads that want S3’s scale and durability but expect a file system interface.
Best suited for:
- Data analytics & ML jobs reading/writing large datasets
- Centralized log aggregation from multiple pods
- Backups & archival storage
- Media processing and high-throughput workloads
Key Characteristics:
- Object store with file-like access: File operations are translated into S3 API calls.
- High throughput: Great for parallel data processing.
- Static provisioning only: You can’t dynamically create S3 buckets — only mount existing ones.
- Not POSIX-compliant: Doesn’t support all file operations like EBS/EFS.
If your workload is data-intensive and benefits from S3’s scale and economics, the Mountpoint driver is an excellent fit.
| Feature | Amazon EBS | Amazon EFS | Amazon S3 |
|---|---|---|---|
| Type | Block storage | File system (NFS) | Object storage (via CSI) |
| Access Mode | Single pod (RWO) | Multi-pod (RWX) | Multi-pod (limited) |
| Performance | Low latency, high IOPS | Shared, elastic, multi-AZ | High throughput, sequential |
| Use Case | Databases, stateful apps | Shared web content, CI/CD, dev tools | Data analytics, logs, backups |
| Provisioning | Static & dynamic | Static & dynamic | Static only |
| AZ Scope | Single AZ | Multi-AZ | Regional (bucket-level) |
Conclusion
Choosing the right storage solution in EKS depends on your workload needs:
- Use EBS for high-performance, single-pod workloads like databases.
- Use EFS for shared, scalable storage where multiple pods need simultaneous access.
- Use S3 (Mountpoint) when you need massive, cost-effective object storage for data-heavy applications.
By aligning your storage choice with your workload requirements, you’ll build an EKS architecture that’s resilient, cost-efficient, and scalable.
References
Refer to my detailed blogs for implementing each of the storage type
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