What is flash storage?

Flash storage solutions range from USB drives to enterprise-level arrays and are not to be confused with random access memory (RAM) or short-term memory. Compared to hard disk drives with moving components, USB flash drives can achieve high-speed response times (for example, microsecond latency). They use nonvolatile memory (NVM), which means that data is not lost when the power is turned off.

Flash storage also uses highly available solid-state drives (SSDs) and requires less energy and physical space than mechanical disk storage.

Today, flash memory is a crucial component found in storage devices (USB flash drives, SD cards), smartphones, mobile devices and digital cameras. 

Flash storage was developed to address the growing need for nonvolatile, compact and energy-efficient storage, as electronic devices became smaller and more portable.

In 1986, Toshiba introduced the first NAND flash memory chip, optimized for compact storage and fast write speed to support storage apps (SSDs, memory cards). In 1993, Intel released NOR flash, which is better suited for apps that require fast data reading, such as embedded systems (boot code, firmware).

Flash memory offered breakthrough performance and quickly disrupted the data storage world, improving on spinning disks and memory cards. As data usage grew and devices became lighter and smaller, flash systems proved the fastest way to store, write, reprogram and transfer digital information.

In 2000, the USB flash drive (also known as a thumb drive) was developed to store and transfer files. This portable device was compact, with far more capacity than earlier storage systems. In 2005, Apple released its first flash-based iPods, accelerating consumer adoption of flash storage technology.

By the late 2000s, flash-based solid-state drives (SSDs) began replacing hard disk drives (HDDs) in laptops and data center environments, offering faster boot times, less power consumption and greater durability.

The evolution of cell technology has marked significant advancements in flash storage capacity. Beginning with single-level cell (SLC) technology storing 1 bit per cell, the industry progressed to multilevel-cell (MLC) technology storing 2 bits per cell in the mid-2000s. Toshiba introduced triple-level cell (TLC) technology in 2009, and Samsung adopted it in 2010, enabling storage of 3 bits of information per cell. Each generation increased storage density while balancing performance considerations.

This shift accelerated in the 2010s with the introduction of 3D NAND technology, which stacks memory cells vertically to increase storage density and reduce cost per gigabyte.

In early 2011, the release of NVMe (nonvolatile memory express) as a flash-native interface further unlocked the potential of flash, enabling ultra-low latency and high-throughput performance across peripheral component interconnect express (PCIe) connections.

In 2018, Micron introduced quad-level cell (QLC) flash drives that use 4 bits of data per cell, increasing density by 33% over TLC. Compared to TLC, QLCs offer better capacity and affordability, but are slower to perform and have lower endurance. They are best suited for read-intensive workloads, such as archival storage, content delivery and AI inference, rather than write-heavy applications such as social media platforms.

For large enterprises, the speed and density of flash have made it the storage technology of choice, and it has largely displaced hard disks as the primary storage medium in data centers. Flash has also become foundational to modern IT infrastructure, powering everything from edge computing to AI model training.

Hard disk drives use electromechanical hardware to store digital information. They are cost-effective and ideal for long-term storage and large files. However, hard disk drives are vulnerable to physical damage over time and have latency issues due to moving components.

Flash memory now assumes functions formerly reserved for computer hard disk drives. For example, when a computer boots up, it runs through a basic input/output system (BIOS) sequence. The firmware that first contained BIOS required read-only memory (ROM) chips, but modern systems use flash memory for BIOS, allowing the contents to be rewritten without extracting chips from the system board.

Flash media can be used to augment this type of storage, enabling applications to work faster and scale further. While HDDs continue to serve as cost-effective archival storage, enterprise workloads increasingly demand the speed and reliability that flash technologies can provide.

Primary storage environments now typically use flash's microsecond latency and high IOPS capabilities, while software-defined storage (SDS) creates virtualized pools that intelligently manage data across both media types. This technological convergence enables organizations to implement hybrid approaches—using flash for performance-critical workloads while directing less frequently accessed data, including SaaS backups, to more economical traditional storage systems.

Flash storage relies on flash memory, a semiconductor that consists of millions of tiny floating-gate MOSFET transistors. These transistors are arranged in a grid pattern similar to city blocks, with each intersection containing a specialized transistor capable of storing information.

The fundamental storage unit in flash memory is a flash memory cell. Each cell contains a floating-gate transistor that can maintain an electrical charge even when power is removed.

What makes these transistors special is their unique two-gate design. The control gate sits on top and manages the flow of electricity, while the floating gate remains isolated by an insulating oxide layer. When data is written to flash memory, a voltage is applied to the control gate, forcing electrons to tunnel through the insulation and become trapped on the floating gate. These trapped electrons change the transistor's electrical properties, representing the binary 1 s and 0 s. Because the floating gate is surrounded by insulation, these electrons remain trapped indefinitely, preserving data access without requiring constant power.

Flash memory falls into low-, medium- and high-density classifications, with higher-density storage packing more cells into the same physical space. This technological advancement has enabled the development of increasingly compact devices with substantial storage capacity, from USB drives to smartphones to solid-state drives that can store terabytes of information.

Flash memory technologies can be implemented in various forms and configurations, each serving different performance needs and use cases. Here's an overview of the major types:

The following are some of the most important flash storage interfaces and protocols:

• NVMe

• SAS and SATA interfaces

• NVMe over Fabrics (NVMe-oF)

Nonvolatile memory express (NVMe) is an interface used to access flash storage over a Peripheral Component Interconnect Express (PCIe) bus. NVMe enables thousands of parallel requests on a single connection. It streamlines the interaction between applications and storage and significantly improves performance. NVMe is now the dominant protocol for high-performance flash storage and is essential for latency-sensitive applications such as real-time analytics and AI workloads.

SAS (serial attached SCSI) and SATA (Serial Advanced Technology Attachment) are two widely used interfaces that connect storage devices to computer systems. While originally developed for hard disk drives, they are also used with flash-based SSDs. SATA is typically found in consumer devices, while SAS is favored in enterprise storage environments for its higher reliability and throughput.

Although newer protocols like NVMe are gradually replacing them, SAS and SATA remain common in legacy systems and budget-conscious deployments. They also help extend the lifespan of existing infrastructure, making them useful in environments undergoing phased upgrades.

NVMe over Fabrics extends the NVMe protocol across network fabrics, such as Ethernet, Fibre Channel or InfiniBand. These network fabrics allow flash storage devices to be accessed remotely with nearly the same low latency and high performance as direct-attached NVMe drives. NVMe-oF is ideal for high-scale, distributed environments, such as modern data centers and cloud infrastructure, where storage needs to be fast, resilient and shareable.

Flash storage is used in a wide range of applications, due to its speed, durability and energy efficiency:

• Enterprise data centers: Large enterprises rely on flash-based solid-state drives (SSDs) and all-flash arrays to support mission-critical workloads, reduce latency and can ensure high availability in data center environments. Flash storage accelerates data processing for real-time analytics, cloud services and artificial intelligence (AI) applications. Flash storage in data centers also enhances data management capabilities enabling fast indexing, retrieval and processing of vast datasets, which optimizes database performance and improves overall system efficiency.

• Mobile devices: Flash storage is essential for smartphones, tablets and laptops, offering fast access to applications, system files and user data. The compact nature of flash memory enables slim, lightweight designs without compromising performance.

• Gaming and graphics: Gamers benefit from the high-speed data transfer of flash storage, enabling quick load times and enhanced graphics processing. Flash storage also enhances the performance of gaming consoles and video editing tools.

• IoT devices: Flash memory is widely used in Internet of Things (IoT) devices for its speed and low power consumption. From smart home gadgets to industrial IoT sensors, flash storage can ensure fast data collection, processing and transmission.

• Edge computing: With the increasing demand for processing data closer to the source, flash storage plays a vital role in edge environments. It allows for fast, onsite data storage and retrieval, which is crucial for applications requiring real-time decision making.

• Cloud storage: Flash storage underpins modern cloud infrastructure, providing high-speed access to vast amounts of data across distributed environments. Its scalability and performance are key drivers in the growing adoption of cloud storage and other services.

• Automotive: Flash memory is increasingly used in vehicles for apps like navigation, entertainment systems and autonomous driving technologies.

In enterprise environments, flash storage has become an important component of data security approaches. The speed of flash storage helps improve backup and restore practices, reducing recovery time when responding to security incidents or system failures.

Many organizations now use air gap backup approaches with removable flash storage devices by physically disconnecting critical backup data from networks to limit exposure to ransomware and other cyberthreats. This physical separation provides an effective layer of protection against network-based attacks.

Flash storage's performance supports cyber resilience through practical applications like data replication, snapshots and encryption with less impact on system performance than traditional storage. In regulated industries, flash storage can help meet compliance obligations through features like WORM (Write Once Read Many) functions and access controls that contribute to the overall security architecture.