The future is here, and it requires removable storage – lots of it.

Trends such as the Internet of Things (IoT), Industrial IoT (IIoT), connected cars and automation are creating overwhelming volumes of data that need to be collected, stored and analyzed. Fast transmission, access and retrieval of the torrents of data from the cloud are straining network infrastructures, making storage on the edge a more viable option for timely, cost-effective and responsive storage and computing.

SD Express memory cards with the PCI Express (PCIe®) interface compliant with the NVM Express® (NVMe™) protocol stretch the capabilities of IoT/IIoT edge ecosystems by delivering portability, scalability and ultra-low latency for reliable data storage and redundancy; future-proof infrastructure investment; agile analytics; and overall greater productivity.

Data Explosion and IoT/IIoT Edge Gateways

The increasing interconnectivity of things is generating astounding amounts of data by the minute. According to the latest statistics from Juniper Research, more than 50 billion devices, sensors and actuators will be connected by 2022, driven mainly by edge computing services. By 2025, the global datasphere will expand to 163 zettabytes, or a trillion gigabytes—10 times the amount of data generated in 2016.

Where should all the data from these connected devices be stored, and how can organizations make data useful at the moment they are needed? The cloud would be the typical answer. However, because data generation is expected to continue at such a frenzied pace, limitations of the cloud infrastructure are requiring that computing and storage is done near or at the source of data—at the edge—to ease network congestion, reduce communication and cloud processing/storage costs, and transform collected data into intelligence faster.

This means gateways are indispensable components of edge storage and computing in an IoT/IIoT ecosystem. Aside from functioning as a bridge through which all data going to or coming from the cloud travels, a gateway also provides processing and analytics closer to where data is generated, delivering critical insights for time-sensitive decision-making in situations where milliseconds count.

Figure 1

Figure 1. An IoT gateway acts as a bridge between IoT/IIoT devices and the cloud, serving as a temporary repository or storage device for data that may not need to go to the cloud.

Edge Gateway Storage Options: Which is the Perfect Fit?

What storage options are available for edge gateways, and how does one choose the right solution? There are several types of edge gateways for different functions, applications, deployments and requirements.

Some gateways are designed to store and process huge amounts of data from extensive sensor networks to deliver advanced edge analytics. They are typically installed in fixed locations and are larger in size to embed more storage capacity. Due to the workload and installation scenarios for which they are built, the storage options for these gateways consist of fast, high-performance and high-capacity embedded SSD or modules. Dell Edge Gateway 5000 Series is an example; its storage options consist of embedded solid-state M.2 modules to deal with complex analysis algorithms, and there is no slot for removable storage media.

Given the diversity of industrial usage, applications and deployments, edge applications do not always require very big, very powerful gateways. Some gateways are designed to meet the requirements of small, compact systems deployed in limited, localized and mobile spaces, providing robust functionality, basic edge analytics and reliable operation in harsh environments. They are usually installed in transportation systems, retail kiosks, vending machines, elevators and industrial automation equipment. An example of this type of gateway is the Dell 3000 Series. Just half the size, one-third the weight and about half to one-third the price of their other products, it is outfitted with e.MMC as embedded storage and a microSD slot for expandable storage.

The following table summarizes how removable and embedded storage solutions fit in different gateway solutions:

Edge Gateway Type Localized Advanced

Sample Deployments
  • Media/retail kiosks
  • IoT mobile/field
  • Single-application processing in manufacturing lines
  • Cargo trucking, bus, train, marine transportation
  • Boiler rooms
  • Inside rooftop HVAC units

Small Large


e.MMC options:
8 GB or 32 GB
M.2, mSATA SSD options:
32 GB – 512 GB


microSD/SD options:
8 GB– 64 GB
SD Express (in potential)

  • Ideal for mobile, limited spaces
  • Robust
  • Basic edge analytics
  • Fixed use cases for modular expansion
  • Ideal for large sensor networks
  • Advanced edge analytics

$$ $$$

The Edge of the SD Form Factor

SD memory cards are perfect for compact edge gateway devices, enabling storage and analytics near or at the source of data. This popular storage solution delivers the following benefits in an IoT/IIoT ecosystem:

  • Offline functionality and fast responsiveness. SD memory cards can provide reliable data storage, and enable autonomous execution of processes even when an Internet connection is unavailable, limited or unstable. Low latency assures fast processing and retrieval, as well as prompt analysis for immediate actionable insight.
  • Removability and flexible expansion. Data collection capabilities can be extended easily by simply swapping memory cards to meet current and future storage needs. There is no need to physically remove or open the system to replace the storage device. On-site firmware or application updates can be done easily by just inserting a new memory card.
  • Small form factor makes the SD memory card an excellent fit for compact systems.
  • Powerful performance at less power consumption. Low power consumption yields substantial cost savings, while industrial temperature rating and IP57/67 compliance (waterproof/dustproof) ensure operational reliability in harsh or extreme environments.

The Revolution: NVMe/PCIe Performance Infused in the SD Form Factor

SD 7.0, the latest SD card specifications released by the SD Association, includes the addition of the SD Express Interface, which integrates the NVMe/PCIe interface with the SD form factor. By leveraging the high-speed interface commonly found in solid state drives (SSDs), SD Express revolutionizes data storage with a breakthrough transfer speed up to 985 MB/s while maintaining all the benefits of the SD form factor.

SD Express memory cards will extend the storage and performance capabilities of IoT/IIoT edge gateways with the enhanced performance and speed of NVMe/PCIe, effectively transforming the card into a removable SSD.

Bolstered by the NVMe/PCIe interface’s superior speed and performance, SD Express can handle the massive amounts of data generated by the IoT/IIoT, such as those from extensive sensor networks, as well as high-resolution, content-rich and speed-hungry applications. SD Express delivers the sequential and random performance for next-generation applications, making it suitable for multi-channel edge computing, including data acquisition from a diversity of sensors, data loggers and video sources; 360-degree virtual and augmented reality applications; and numerous automotive applications. SD Express open new possibilities for edge gateways, enabling applications that greatly improve personal experiences as well as for enterprise, industrial and government systems through accelerated processing and scalability.

SD Express also is a good candidate to replace the M.2 in products like tablets. These types of products will easily support SD Express because they already have all the supported PCIe/NVMe infrastructure – and even if the SD Express does not fully replace the M.2 in a product, it will be easy to have SD Express added as its removable memory for additional flexibility.

The edge is getting sharper, and the new SD Express will clearly make the cut.

Crystal Chang is the leader of ATP’s memory card business unit. Chang leads memory card development, designs and implementation in automotive, automation, avionics, medical, IoT, test and measurement, and industrial applications. Chang can be reached at

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