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iSCSI (Internet Small Computer Systems Interface)

Terms related to simplyblock

RAID Software-Defined Storage (SDS) RDMA (Remote Direct Memory Access) DPDK (Data Plane Development Kit) iSCSI (Internet Small Computer Systems Interface) 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 iSCSI?

iSCSI (Internet Small Computer Systems Interface) is a storage networking protocol that enables the transport of block-level data between servers and storage devices over standard TCP/IP networks. It allows organizations to build cost-effective Storage Area Networks (SANs) using existing Ethernet infrastructure without the need for specialized hardware. By encapsulating SCSI commands into IP packets, iSCSI provides reliable data transmission across LANs, WANs, or the internet.

iSCSI is widely used in enterprise environments for centralized storage management, offering flexibility, scalability, and compatibility with various operating systems. Compared to traditional direct-attached storage (DAS), iSCSI enables greater resource utilization and simplified storage provisioning, making it a popular choice in virtualization, database hosting, and backup scenarios.

How does iSCSI work?

iSCSI operates by transmitting SCSI commands over IP networks. In a typical setup, an iSCSI initiator (usually the client or host machine) communicates with an iSCSI target (the storage device) over Ethernet. The initiator sends SCSI commands encapsulated within TCP/IP packets to the target, which processes these commands and responds with the requested data.

The key components of an iSCSI architecture include:

  • Initiator: The client requesting access to the storage.
  • Target: The storage system providing block-level storage.
  • LUN (Logical Unit Number): A unique identifier for a specific portion of storage on the target.
  • iSCSI Qualified Name (IQN): A unique identifier for initiators and targets in an iSCSI network.

Because iSCSI uses standard networking, it integrates easily with existing IP-based infrastructures, reducing the need for expensive Fibre Channel solutions.

Benefits of iSCSI

iSCSI delivers several advantages to organizations seeking flexible and affordable networked storage:

  • Cost-effectiveness: Utilizes standard Ethernet hardware, eliminating the need for costly Fibre Channel components.
  • Scalability: Easily expand storage capacity by adding new targets without major infrastructure changes.
  • Compatibility: Supports a wide range of operating systems, hypervisors, and applications.
  • Simplified management: Centralizes storage administration across distributed environments.
  • Remote storage access: Enables secure data access across different geographic locations.

iSCSI vs. NVMe/TCP

While iSCSI has been a reliable protocol for years, newer technologies like NVMe/TCP have emerged, offering improved performance. Here’s a simple comparison:

Before diving into the table, it’s essential to understand that while both protocols transport block storage over IP networks, NVMe/TCP is optimized for modern workloads and flash storage, whereas iSCSI was originally designed with traditional spinning disks in mind.

FeatureiSCSINVMe/TCP
LatencyHigher, due to protocol overheadSub-millisecond latency
PerformanceAdequate for traditional workloadsHigh IOPS, optimized for flash
HardwareStandard EthernetStandard Ethernet
CPU UtilizationHigherLower
Best Use CaseLegacy workloads, backupsHigh-performance databases, AI/ML

Common use cases for iSCSI

iSCSI continues to be relevant in several storage scenarios, especially when cost and simplicity are priorities. Typical use cases include:

  • Virtual machine storage for platforms like VMware and Hyper-V.
  • Centralized storage for database servers.
  • Backup and disaster recovery solutions.
  • Remote office storage consolidation.

For organizations considering modern alternatives, technologies like NVMe/TCP and Software-Defined Storage (SDS) offer higher performance and better scalability for cloud-native and containerized environments.

Simplyblock and modern alternatives to iSCSI

At Simplyblock, we specialize in providing high-performance, distributed block storage solutions built on cutting-edge protocols like NVMe/TCP. Compared to traditional iSCSI systems, Simplyblock offers sub-millisecond latency, superior scalability, and seamless Kubernetes integration via our CSI driver.

For businesses transitioning from legacy iSCSI setups, Simplyblock delivers a modern, reliable, and cost-efficient path forward. With built-in erasure coding, high-availability features, and Kubernetes-native storage, our platform ensures optimal performance across a variety of workloads.

Further reading

Explore more storage concepts and solutions:

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