When deploying persistent storage solutions for k3s clusters on VPS infrastructure in 2025, three primary options dominate the landscape: Longhorn, OpenEBS, and Rook-Ceph. Each solution offers unique advantages in terms of distributed storage capabilities, performance characteristics, and operational complexity. This comprehensive comparison examines performance benchmarks, resource overhead, data safety guarantees, and helps you choose the optimal storage solution for your Kubernetes workloads.
Architecture Overview
Longhorn: Simplicity First
Longhorn, developed by Rancher, follows a microservices architecture with separate engine and replica processes. Each volume consists of a controller and multiple replicas distributed across nodes. The solution provides block-level replication and supports features like snapshots, backups, and disaster recovery.
- Deployment Model: DaemonSet-based with minimal external dependencies
- Data Path: Direct block device access through iSCSI
- Replication: Synchronous replication with configurable replica count
- Management: Web UI and kubectl integration
OpenEBS: Modular Approach
OpenEBS offers multiple storage engines including Mayastor (NVMe-oF), cStor, Jiva, and LocalPV. This modular architecture allows selecting the appropriate engine based on performance requirements and infrastructure capabilities.
- Storage Engines: Mayastor for high performance, cStor for enterprise features
- Data Path: Multiple options including NVMe-oF and iSCSI
- Replication: Engine-dependent with synchronous and asynchronous options
- Management: Kubernetes-native with custom resources
Rook-Ceph: Enterprise Grade
Rook-Ceph combines the battle-tested Ceph distributed storage system with Kubernetes-native orchestration through Rook operators. This solution provides unified block, object, and file storage with enterprise-grade features.
- Storage Types: Block (RBD), Object (RGW), and File (CephFS)
- Data Path: Native Ceph protocols with kernel and userspace clients
- Replication: Configurable replication and erasure coding
- Management: Operator-based with extensive CRDs
Performance Benchmarks
IOPS and Throughput Comparison
Based on standardized benchmarks using fio on identical 3-node clusters with NVMe storage:
Random Read/Write IOPS (4K blocks):
- Longhorn: 15,000-20,000 IOPS read, 12,000-16,000 IOPS write
- OpenEBS Mayastor: 45,000-60,000 IOPS read, 35,000-50,000 IOPS write
- Rook-Ceph: 25,000-35,000 IOPS read, 20,000-30,000 IOPS write
Sequential Throughput (1MB blocks):
- Longhorn: 800-1,200 MB/s read, 600-900 MB/s write
- OpenEBS Mayastor: 2,500-3,500 MB/s read, 2,000-3,000 MB/s write
- Rook-Ceph: 1,800-2,800 MB/s read, 1,400-2,200 MB/s write
Latency Characteristics
Average latency measurements under moderate load conditions:
- Longhorn: 2-4ms read latency, 3-6ms write latency
- OpenEBS Mayastor: 0.5-1.5ms read latency, 1-2.5ms write latency
- Rook-Ceph: 1-3ms read latency, 2-5ms write latency
Resource Overhead Analysis
Memory Consumption
Per-node memory overhead for base installation on a 3-node cluster:
- Longhorn: 200-400MB per node (manager + driver components)
- OpenEBS: 150-600MB per node (varies by engine selection)
- Rook-Ceph: 1-2GB per node (OSD + monitor + manager daemons)
CPU Utilization
Average CPU consumption during normal operations:
- Longhorn: 0.1-0.3 CPU cores per node
- OpenEBS: 0.05-0.5 CPU cores per node (engine-dependent)
- Rook-Ceph: 0.5-1.5 CPU cores per node
Network Overhead
Additional network traffic for replication and management:
- Longhorn: 2-3x write amplification for 3-replica setup
- OpenEBS: 1.5-3x amplification depending on engine and configuration
- Rook-Ceph: 2-4x amplification with monitoring and heartbeat traffic
Data Safety and Reliability
Consistency Models
Longhorn provides strong consistency through synchronous replication with configurable replica counts. The system ensures all replicas acknowledge writes before completion, preventing data loss during node failures.
OpenEBS consistency depends on the selected engine. Mayastor offers strong consistency with NVMe-oF, while cStor provides eventual consistency with configurable sync policies.
Rook-Ceph delivers strong consistency through RADOS with configurable consistency levels. The system supports both immediate and relaxed consistency modes based on client requirements.
Disaster Recovery Capabilities
- Longhorn: Built-in backup to S3-compatible storage, point-in-time snapshots
- OpenEBS: Engine-specific backup solutions with Velero integration
- Rook-Ceph: Native RBD snapshots, cross-cluster replication, and multi-site disaster recovery
Deployment and Operational Complexity
Installation Ease
Longhorn wins in simplicity with single-command installation via Helm or kubectl. The solution requires minimal configuration and provides immediate usability.
OpenEBS offers moderate complexity with engine selection requiring upfront planning. Mayastor installation demands specific kernel versions and hugepage configuration.
Rook-Ceph presents the highest complexity with extensive configuration options for OSDs, pools, and placement groups. However, it provides the most comprehensive feature set.
Maintenance Overhead
- Longhorn: Minimal maintenance with automatic health checks and repair
- OpenEBS: Moderate maintenance depending on engine selection
- Rook-Ceph: Requires understanding of Ceph concepts for optimal maintenance
Use Case Recommendations
Choose Longhorn When:
- Prioritizing operational simplicity and ease of management
- Working with small to medium-scale deployments
- Requiring straightforward backup and disaster recovery
- Operating with limited storage administration expertise
Choose OpenEBS When:
- Demanding maximum performance with NVMe-oF (Mayastor)
- Needing flexible storage engine options for diverse workloads
- Operating cloud-native environments with automated provisioning
- Requiring fine-grained performance tuning capabilities
Choose Rook-Ceph When:
- Requiring unified block, object, and file storage
- Operating large-scale, enterprise-grade deployments
- Needing advanced features like erasure coding and multi-site replication
- Having experienced Ceph administration capabilities
VPS Cluster Considerations
When deploying these solutions on VPS infrastructure, consider network latency between nodes, available IOPS from underlying storage, and bandwidth limitations. Production-ready k3s clusters benefit from dedicated storage networks and consistent performance characteristics across nodes.
For cost-effective deployments, Longhorn provides the best balance of features and resource efficiency. High-performance workloads may justify OpenEBS Mayastor’s additional complexity, while enterprises requiring comprehensive storage services should consider Rook-Ceph despite higher resource requirements.
Conclusion
The choice between Longhorn, OpenEBS, and Rook-Ceph depends on your specific requirements for performance, operational complexity, and feature needs. Longhorn excels in simplicity and ease of use, OpenEBS Mayastor delivers superior performance for demanding workloads, and Rook-Ceph provides enterprise-grade features with comprehensive storage services.
For most VPS-based k3s deployments in 2025, Longhorn offers the optimal balance of functionality, performance, and operational overhead. Consider evaluating these solutions in your specific environment to make the best choice for your distributed storage requirements.
