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NVMe Latency Explained

Terms related to simplyblock

SPDK Copy-On-Write (CoW) NVMe Latency Storage Latency IOPS (Input/Output Operations Per Second) NVMe over TCP (NVMe/TCP) Thin Provisioning Distributed Storage System Write-Ahead Log (WAL) TiDB Interbase ArangoDB Memgraph TDengine Qdrant CouchDB Hazelcast DuckDB CockroachDB CrateDB SAP Hana Teradata Snowflake Databricks Weaviate Pinecone ScyllaDB Marqo RocksDB Aerospike Singlestore Timescale MariaDB Apache Cassandra Couchbase InfluxDB Neo4j Clickhouse Elasticsearch Redis MySQL Microsoft SQL Server Oracle MongoDB PostgreSQL Open-Source Storage MinIO Longhorn Amazon EBS Rook OpenEBS NVMe-oF Kubernetes OpenStack Ceph

What is NVMe Latency?

NVMe (Non-Volatile Memory Express) latency refers to the time delay in processing data requests between an NVMe-based storage device and the system. It is measured in microseconds (µs) and is significantly lower than traditional storage interfaces like SATA and SAS. Low latency is one of the defining characteristics of NVMe, making it ideal for high-performance applications such as databases on Kubernetes, artificial intelligence, and real-time analytics.

How NVMe Achieves Low Latency

NVMe storage achieves ultra-low latency by leveraging the following:

  • Parallelism and Queues: NVMe supports up to 64K parallel command queues, each capable of holding 64K commands. This allows modern CPUs to handle multiple storage operations simultaneously, reducing processing delays.
  • PCIe Interface: Unlike SATA SSDs, which operate at 6Gbps, NVMe uses PCIe, offering speeds of up to 16Gbps per lane, with multiple lanes providing aggregate bandwidth.
  • Direct CPU Communication: NVMe eliminates the need for intermediate storage controllers, reducing processing overhead and accelerating data transfers.

NVMe Latency vs. Other Storage Protocols

FeatureNVMeSATA SSDHDD
Read Latency~20 µs~100 µs2-5 ms
Write Latency~30 µs~200 µs5-10 ms
Queue Depth64K queues × 64K commands32 commands1 command
BandwidthUp to 16GB/s (PCIe 4.0)600MB/s~150MB/s

Compared to HDDs and even SATA SSDs, NVMe latency is nearly negligible, making it a preferred choice for latency-sensitive workloads.

Factors Affecting Latency

While NVMe is designed for high-speed data access, certain factors can influence its latency:

  1. Network Transport (NVMe-oF vs. NVMe/TCP): NVMe over Fabrics (NVMe-oF) minimizes latency further by leveraging RDMA, while NVMe/TCP, though cost-effective, has slightly higher latency due to network stack overhead.
  2. Queue Depth and Workload: Higher queue depths allow NVMe to process multiple requests simultaneously, but excessive workloads can lead to queue saturation, slightly increasing latency.
  3. Firmware and Controller Efficiency: High-performance NVMe drives have optimized firmware to minimize internal processing delays.
  4. Host System Configuration: CPU power management, PCIe slot configuration, and DRAM caching can impact NVMe response times.
  5. Storage Network Architecture: In distributed storage systems, network topology and bandwidth can influence end-to-end latency.

Optimizing NVMe for Minimal Latency

To achieve the lowest possible NVMe latency:

  • Use NVMe over RDMA (RoCE or InfiniBand) to eliminate unnecessary network overhead.
  • Enable Direct Storage Access (DSA) to bypass kernel-level processing.
  • Optimize PCIe Slot Allocation to prevent bandwidth bottlenecks.
  • Leverage Software-Defined Storage (SDS) for better scalability and latency control.

NVMe and Simplyblock

Simplyblock utilizes NVMe technology to deliver sub-millisecond latency storage solutions optimized for modern applications. By integrating NVMe/TCP, Simplyblock ensures high-speed data access without requiring specialized RDMA hardware, making it a cost-effective and scalable solution for enterprises.

For more details on NVMe storage and its impact on modern workloads, check out Simplyblock’s NVMe Storage Overview.