What kind of redundancy: Mirrored server or edge devices?
Control system architectures take many forms, and two high-availability opportunities for control system designers are a mirrored server and twin edge devices. How should someone choose between these architectures? Stratus representatives Jason Andersen, vice president strategy & business line management; John B. Vicente Jr. PhD, chief technology officer; and Stephen Greene, vice president global marketing, explained some similarities and differences in the two architectures. They made the comments to CFE Media and Technology publications at Rockwell Automation’s Automation Fair 2019.
Server or edge?
For a design in a more environmentally secure area, such as a control room or control enclosure, Stratus ftServer has two servers in one box, mirrored, for zero data loss if one side fails. These often are used in industries with high regulatory penalties for data loss of product quality or original information. These include food and beverage, pharmaceuticals, oil and gas and energy industries.
Sales of edge devices has doubled in 3 years. The Stratus ztC Edge computing platform is a smaller, rugged form factor for use on a plant floor, on machines, and in other harsh environments, like a stone quarry. Stratus Edge devices can be ready to load applications within 30 minutes without needing experts. Security is built-in (a trusted platform module is used), and management and monitoring are included. Ports can be locked, a firewall is included, and penetration testing meets ISA cybersecurity standards in preliminary testing.
Available software offers virtualization, supervisory control and data acquisition (SCADA), human-machine interface (HMI), database, and preventive maintenance capabilities.
Photo shows a four 4 virtual machine (VM) server configuration (bottom); a 6 VM is available in a larger size.
The edge device has a web-based user interface and is pre-packaged and pre-configured. A system integrator said it can be integrated within a day instead of a few days for other devices or systems. The edge product also includes two devices for redundancy that are often placed in two locations.
The Stratus experts said these edge devices are designed to offer more capabilities than an industrial PC (iPC). Greene added the zTC Edge serves as a computing platform and not just a gateway communication device. The server is an assembled product and built organically to meet customer needs.
While the server and edge platforms offer computing capabilities, the server is more costly than the smaller form factor machine, providing control room computing capabilities, as opposed to edge devices with a more finite capacity. As architectures progress, Greene suggested, more industries may get to “full enlightenment” of autonomous computing (also known as fog computing).
Video: Edge computing tips
In a 2-minute video, Anderson explained three tips about edge and server-based industrial computing to aid understanding.
- Is it a secure system? Increasingly, edge devices are exposed to the cloud and outside services. It’s running trusted software and has controlled network connectivity.
- Where will data be processed? Systems are available to process data in a control room setting or on the edge, where the process is occurring.
- Work with software partners to ensure the system runs well. It’s getting more difficult to find talent to program and maintain systems. They should be easy to install, use and maintain.
Jason Andersen, Stratus vice president strategy business line management, explains three tips to consider when choosing an industrial computing platform. Courtesy: McKenzie Burns, CFE Media and Technology
Mark T. Hoske is content manager, Control Engineering, CFE Media and Technology, firstname.lastname@example.org.
KEYWORDS: Edge computing, industrial server
How to decide between server or edge computing
Pre-packaged edge devices can build-in security
Video offers three industrial computing tips.
Have redundant servers or duel edge computing systems been among control architecture options?