Your Next Kubernetes Storage Upgrade Starts Here
Rook-Ceph handles the complexity. Longhorn handles the small clusters. OpenEBS handles the confusion. simplyblock handles the actual workload.
Open-source Kubernetes storage options each solve part of the problem. Rook-Ceph adds Kubernetes operators to Ceph's existing complexity. Longhorn provides HA block storage for small clusters but replicates entire volumes across the network. OpenEBS bundles four storage engines with different feature sets and maturity levels.
simplyblock is purpose-built for NVMe block storage on Kubernetes: sub-200-microsecond latency over NVMe/TCP, per-PVC IOPS limits, erasure-coded data protection, and a single storage engine with predictable behavior. No deprecated engines, no adapters, no Ceph internals.
The Hidden Costs of Open-Source Kubernetes Storage
Rook-Ceph: Kubernetes Wrapper, Ceph Internals
Rook automates Ceph deployment on Kubernetes, but Ceph's operational complexity (CRUSH maps, placement groups, OSD tuning, recovery storms) does not disappear. Platform teams inherit a distributed storage system built for a different era.
Longhorn: Full-Volume Replication at Network Cost
Longhorn replicates entire volume contents across nodes synchronously. For large database volumes, every write crosses the network multiple times. This network amplification limits throughput and adds latency that grows with volume size.
OpenEBS: Four Engines, Diverging Maturity
OpenEBS ships LocalPV, Jiva, cStor, and Mayastor in the same project. Each engine has different HA guarantees, feature sets, and operational interfaces. Teams evaluating OpenEBS spend significant time determining which engine fits which workload.
No Per-PVC QoS in Any Open-Source Option
None of Rook-Ceph, Longhorn, or OpenEBS enforce per-PVC IOPS or throughput limits. All PVCs compete for the shared I/O pool. When a backup job or batch workload runs, production database latency degrades with no enforcement mechanism to prevent it.
What is simplyblock?
NVMe-native, purpose-built for Kubernetes, one storage engine.
Architecture and Transport
simplyblock is a software-defined NVMe block storage system built from scratch for Kubernetes workloads. It uses NVMe/TCP as the storage transport, delivering sub-200-microsecond latency over standard Ethernet without specialized hardware.
Open-source alternatives use older or fragmented protocols. Rook-Ceph relies on Ceph RBD over RADOS. Longhorn uses iSCSI, with NVMe/TCP only available in the experimental v2 engine. OpenEBS engine selection determines the transport: LocalPV has no HA, cStor uses iSCSI, and Mayastor uses NVMe-oF. Each engine requires separate operational knowledge, and there is no unified management plane across engines.
Data Protection and Storage Efficiency
simplyblock uses erasure coding for data protection. A 4+2 scheme tolerates two node failures while using only 1.5x the raw data size. Per-PVC IOPS and throughput limits are enforced at the storage layer via StorageClass parameters. Production databases get guaranteed I/O rates. Batch workloads are rate-limited without manual scheduling or backup windows.
Longhorn uses full-volume synchronous replication at 3x storage overhead. Rook-Ceph supports erasure coding but requires manual CRUSH map configuration. OpenEBS data protection varies by engine: LocalPV has none, Jiva and cStor use replication, Mayastor uses NVMe-oF replication. None of the three enforce per-PVC QoS, so noisy-neighbor effects from batch workloads directly impact production latency with no remedy.
simplyblock Capabilities
NVMe/TCP Transport, No Specialized Hardware
Storage runs over standard Ethernet using NVMe/TCP. No InfiniBand, no Fibre Channel, no RoCE NICs required. Sub-200-microsecond latency on commodity hardware.
Erasure Coding Instead of Full Replication
Configurable erasure coding (4+2, 8+2, and others) protects data across nodes with 1.5x storage overhead instead of 3x. Significant cost reduction for large-volume workloads.
Per-PVC IOPS and Throughput Limits
Quality of service enforced at the volume level in the storage layer. Production workloads get guaranteed I/O. Batch workloads are rate-limited without manual scheduling.
Instant Copy-on-Write Snapshots
Snapshots complete in under one minute regardless of volume size. No I/O pause. CSI VolumeSnapshot compatible. Works with Velero, Kasten K10, and standard backup orchestrators.
Cross-Cluster Replication for DR
Synchronous and asynchronous volume replication to secondary clusters. Storage-layer failover promotes the replica to primary. RTO in minutes, not hours of restore time.
Prometheus Metrics and Per-PVC Observability
Native Prometheus endpoint with per-volume IOPS, latency (P50/P99), throughput, and queue depth. No agents, no sidecars. Pre-built Grafana dashboard templates included.
Questions and Answers
Why is simplyblock faster than Rook-Ceph for Kubernetes workloads?
Ceph's RBD block storage layer was not designed for NVMe or for Kubernetes-native workloads. Rook adds a Kubernetes operator on top of Ceph but does not change the underlying I/O path. simplyblock uses NVMe/TCP as the storage transport from the start, delivering sub-200-microsecond latency rather than the multi-millisecond latency typical of Ceph-based storage. Additionally, simplyblock's erasure coding implementation is designed for the throughput and CPU profiles of NVMe workloads, not spinning disk.
Is Longhorn a good alternative to simplyblock for small clusters?
Longhorn is a reasonable choice for small Kubernetes clusters with modest I/O requirements. It provides HA block volumes with a simple operational model. The limitation is scalability: Longhorn replicates entire volume contents synchronously across nodes, which means write amplification grows with volume size and network bandwidth consumption scales with write throughput. For clusters with database workloads, high I/O requirements, or strict latency targets, simplyblock provides the performance headroom that Longhorn cannot.
Which OpenEBS engine should we use for production databases?
OpenEBS Mayastor (now OpenEBS Replicated PV Mayastor) is the recommended engine for production database workloads: it uses NVMe-oF and provides HA replicated block volumes. However, Mayastor has different operational characteristics than cStor or Jiva, and teams migrating between engines face significant migration work. simplyblock provides equivalent NVMe-native performance with a single, consistent storage engine and does not require engine selection or future engine migration.
Does simplyblock have community or open-source options?
simplyblock is a commercial product with subscription licensing. Teams evaluating simplyblock can contact us to discuss a proof-of-concept deployment. For teams specifically looking for open-source options with commercial support available, Rook-Ceph has a strong ecosystem of vendors offering support contracts.
How does migration from Rook-Ceph or Longhorn to simplyblock work?
Migration is typically done workload-by-workload using standard Kubernetes tooling. simplyblock provisions new volumes via its CSI driver. Application workloads are migrated by stopping writes to the old volume, taking a snapshot or backup, restoring to the new simplyblock volume, and redirecting the application. For database workloads, the migration path uses standard database-level backup and restore rather than block-level volume copy. Most teams complete the migration incrementally over several weeks during normal maintenance windows.
Can we run simplyblock alongside Rook-Ceph on the same cluster?
Yes. simplyblock's CSI driver operates as a separate StorageClass. You can provision new workloads onto simplyblock volumes while existing workloads continue to use Rook-Ceph volumes. This allows incremental migration without a big-bang cutover.
Not sure if simplyblock is right for your team?
Ask your favorite AI to compare simplyblock with open-source Kubernetes storage options including Rook-Ceph, Longhorn, and OpenEBS.
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