Frequently Asked Questions (FAQ)

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What is Stratus announcing?

Stratus is announcing on December 7 the general availability of a new software update for its ztC Edge computing product line. Stratus Redundant Linux version 2.2 offers customers an enhanced REST API, the latest security patches, and one-click enablement for a new, web-based systems management tool – ztC Advisor. Current customers are encouraged to upgrade to this latest version, to take advantage of these new features and enhancements.

Why are these new features and enhancements important?

With SRL 2.2, improvements in interoperability, security and manageability help customers further reduce their cost of operation and maintenance, improve productivity, and minimize risk. An enhanced REST API, with more granular information at the VM level, enables admins to better optimize application performance and resource utilization. SRL 2.2 incorporates Stratus’s latest security patches and updates, addressing nearly 200 known vulnerabilities and bugs to deliver a more secure, reliable operating platform for its ztC Edge solutions. Lastly, one-click enablement for ztC Advisor, a new web-based systems management tool, enables admins of all backgrounds that need to centrally manage multiple ztC Edge platforms and ensure their availability, become productive faster.

What is ztC Advisor?

ztC Advisor is a new web-based edge systems management tool that makes it easier for administrators of all backgrounds – Operations and IT – to remotely manage their ztC Edge computing infrastructure at scale. ztC Advisor simplifies the remote, centralized monitoring and management of multiple ztC Edge platforms. Through a secure, web based portal, customers can quickly and easily view the health and utilization of their entire ztC Edge inventory, helping them remotely triage issue, improve productivity, and mitigate risk. Starting Dec 7, ztC Advisor will be offered to Stratus customers as a preview product. More information is available at

What does it mean that ztC Advisor is being offered as a “preview” product?

In order to gather information about this new product, ztC Advisor is initially being offered to current customers as a free preview. For a limited time, current customers with active support and maintenance contracts will be able to register to use ztC Advisor for no additional cost, in exchange for providing Stratus feedback about their experience. All new customers purchasing ztC Edge platforms are encouraged to register and try ztC Advisor. All current customers using ztC Edge platforms running SRL 2.1 (or earlier) are encouraged to update their systems to SRL 2.2 and take advantage of this new offering.

What is Stratus’s ztC Edge solution?

Stratus ztC Edge is a secure, rugged, highly automated computing platform that helps understaffed organizations improve productivity, increase operational efficiency, and reduce downtime risk at the edge. “ztC” stands for “zero touch computing”. With its built-in virtualization, automated protection, industrial interoperability, OT manageability, and field serviceability, ztC Edge delivers highly available virtualized edge applications quickly and easily.

Who is the ztC Edge for, and what are its main benefits?

The solution is designed for both Operations and IT staff that need to quickly deliver reliable edge and IoT (Internet of Things) applications in remote, resource constrained environments. Its primary benefit is greater productivity through increased resource utilization, improved operational efficiency, and reduced downtime.

Where can I get ztC Edge? In what are the specific countries and languages is it currently supported?

ztC Edge is supported globally and localized into most major Tier 1 languages. For a current list of supported languages and countries, please visit our localization status page.

Which product safety and quality certifications does ztC Edge comply with or adhere to?

Stratus ztC Edge is currently certified under most global programs, like FCC, CE, VCCI, CCC, and others. The ztC Edge 110i model is Class I Division 2 (CI D2) certified, ensuring that it can be safely deployed in potentially hazardous environments with an approved enclosure. For a current list of environmental certifications, please visit our certification status page.

What are Stratus ztC Edge’s key features?

Its key features are its built-in virtualization, simplified security,  industrial interoperability, OT manageability, rugged redundant nodes, automated protection, field serviceability, and optional and managed support services. Differentiated from other edge computing platforms by its operational simplicity and ease of use, the level of protection it provides, and its breadth of automated capabilities, ztC Edge helps both OT and IT staff deliver highly reliable virtualized edge applications quickly and easily, allowing understaffed organizations to increase productivity and efficiency, while lowering downtime risk. For more information about ztC Edge, please visit the ztC Edge product homepage on, or download and read the ztC Edge data sheet.

What applications do companies typically run on ztC Edge?

Stratus ztC Edge is designed to deliver highly reliable edge computing applications quickly and easily, such as industrial control applications (e.g. SCADA/HMI, historian) from Rockwell, Aveva (Wonderware), GE, and Inductive Automation, and building management systems from companies like Schneider Electric and Gallagher. It can also support many other emerging edge applications – ThinManager remote desktop virtualization software from Rockwell, analytics frameworks like FogHorn’s Lightning EdgeML.

Can ztC Edge be ordered, or customized with different processors, memory, and storage?

Yes and no. Stratus offers two different hardware models – the ztC Edge 100i and ztC Edge 110i – with different processor, storage, and networking capacities. But the models themselves are not further customizable. Fixed configurations, and a minimum set of product SKUs simplify order entry and fulfillment. The platforms are available as single node versions, for customers that don’t immediately require a highly available or fault tolerant computing platform, or for those that want to add redundancy later. Redundant systems are also available for purchase. For a summary of the similarities and differences between the two hardware models, please visit the ztC Edge product homepage on, or download and read the ztC Edge data sheet.

What are the Windows licensing requirements for ztC Edge if I want to run Windows guest operating systems on them?

Stratus ztC Edge requires at least one Windows license, which will support up to 2 VMs. For a redundant deployment, you will need to acquire two Windows licenses (one for each ztC Edge node) at a minimum. The two licenses will provide support for up to four VMs on a redundant ztC Edge system. If customers want to run 5 to 8 small VMs on a redundant ztC Edge system, they will need to acquire two more Windows licenses (one more for each node).

Are current ztC Edge customers entitled to Stratus Redundant Linux version 2.2?

Yes, if they have an active support contract. Current ztC Edge customers running Stratus Redundant Linux (SRL) versions 1.x or 2.x that also have an active System Support or System Health subscription are entitled to download, upgrade, and use SRL 2.2 for no additional cost. Their support subscription entitles them to software patches and upgrades. Customers that are running SRL 2.1 can use the easy upgrade feature available in their ztC Edge Console to upgrade their system. Customers that are running any earlier version of SRL (e.g. version 1.x) should contact Stratus Support to confirm their upgrade process.

Earlier you mentioned that customers with active support contracts can upgrade to SRL 2.2, as well as register to use ztC Advisor, for no additional charge. What are the support contract options that are available with ztC Edge?

Stratus offers two annual (and renewable) support options – System Support and System Health – to help customers maximize their ztC Edge return on investment.

Customers subscribing to System Support services receive 24×7 web and phone-based technical support services with a 30-minute response SLA for critical issues. They also receive root cause problem determination services, access to patches, updates, knowledgebase, and other resources through a secure, self-service portal, and 3-day advance parts exchange. Unlike a warranty parts replacement, Stratus ships to customers replacement nodes before receiving a node in exchange.

Customers subscribing to System Health services receive 24×7 system monitoring, alert triage, system log reviews, predictive failure analysis, and media retention services. System Health services are more proactive in nature and designed to identify and fix issues before they become more serious problems. System Health is an add on subscription service to System Support.

You mentioned that Stratus Redundant Linux includes its own virtualization platform. On what technology is the virtualization platform based?

The system software for ztC Edge, Stratus Redundant Linux, is based in part on the CentOS distribution and KVM hypervisor. Although it is based on open source software, it has been customized by Stratus. For this reason, customers wanting to update their systems should only apply patches that they’ve received from Stratus. The addition of an availability layer, along with a management tool, the ztC Edge Console, enables the management of an individual system and its VMs.

What operating systems are supported for virtual guests?

ztC Edge supports most major Windows and Linux operating systems as virtual guests. For a current list of supported guest operating systems, please visit our guest OS support status page.

What is the capacity of a ztC Edge solution? How many applications can you run on it simultaneously?

The number of applications that can simultaneously be operated on ztC Edge depends on several factors, including the application’s resource requirements, its performance expectations, and desired availability level.

For example, a single Stratus ztC Edge platform can be set up to support three moderately sized VMs and deliver acceptable performance when configured using a SCADA application’s default settings. For example, each 100i node comes with 4 Intel i7 hyperthreaded cores (which translates into 8 virtual CPUs), 32 GB of memory, and 512 GB of SSD storage. The ztC Edge operating system itself requires 2 virtual CPUs, 2 GB of RAM, and about 20% of the available application memory and storage if deployed in redundant mode. A redundant ztC Edge 100i system might be configured with 3 VMs, each sized with 2 virtual CPUs and 8 GB of RAM. One VM with 60 GB of storage might be used for a 10,000 tag SCADA/HMI workload, with data being collected at 1 tag/sec. The second VM with 250 GB of storage would support a 10,000 tag local Historian, at default compression. The third VM with 90 GB of disk would be used to run remote desktop services, supporting 3 concurrent users or sessions.

For more information about your specific use case, or for the latest sizing guides, please contact your local Stratus partner or customer success engineer.

Are 3 VMs the maximum number ztC Edge will support?

No. The total number of VMs that are supported depends on the applications that are running, as well as your performance requirements. ztC Edge has been designed, however, to support 3 VMs in a typical edge computing environment. If a customer is running more lightweight VM use cases, then more than 3 VMs are possible.

Can the hypervisor in Stratus Redundant Linux use unmodified VMware images?

Yes. Virtual appliances (pre-configured virtual machine images) in both OVF and OVA formats are supported by ztC Edge’s virtualization host, including those templates formatted for VMware. When VMware images, including UEFI VMs (unified extensible firmware interface) are retrieved using ztC Edge’s management tool (ztC Edge Console), they are automatically imported into the format required for ztC Edge and then started.

Is ztC Edge a fault tolerant solution?

Yes, it can be. Redundant ztC Edge 110i systems can be configured to support fault tolerant (FT) or highly available (HA) workloads, at the VM level. In fact, customers can run FT and HA workloads simultaneously, on the same redundant 110i system, as long as they are on different VMs. This flexibility allows customers to match the level of availability to the criticality of their workloads and optimize resource utilization.

ztC Edge 100i models support HA workloads (when deployed as a redundant system), but they don’t support fault tolerant workloads. This is because the 10 GbE interconnects required for fault tolerance are only available with 110i hardware.

Does Stratus offer other fault tolerant solutions? What are the similarities and differences between ftServer and ztC Edge?

Yes, Stratus offers another fault tolerant solution called ftServer. In fact, the “ft” in “ftServer” stands for “fault tolerant”.

ztC Edge is purpose-built for Edge environments and well suited for moderately-sized edge applications. Its compact, rugged form factor allows it to be deployed right on the plant floor — on a wall, DIN rail, cabinet, control panel, or piece of production equipment. ztC Edge comfortably supports the visualization and control of environments with up to 10,000 tags and 3 concurrent users.

ftServer is designed for larger industrial control applications, and the greater capacity of its 4U rack mount form factor plus its support for third-party virtualization platforms and mass storage options makes it better suited for larger mission critical workloads deployed in regional data centers or edge control rooms.

Do the two ztC Edge nodes running in fault tolerant mode act like a single logical system (like ftServer) or is one a primary and the other a standby?

ztC Edge implements fault tolerance differently than ftServer. ztC Edge uses a software-based approach, with checkpointing, while ftServer uses a hardware based approach, with FPGAs.

When operating in fault tolerant mode, the two nodes in a ztC Edge solution act like a redundant system, continually replicating all data written to disk, all data in memory, and all CPU states, across both nodes so that in the event of a catastrophic failure in one node, VMs can resume on the other surviving node exactly where the first node left off. The second node is in an “active standby”, or “ready” mode, continually being updated and ready to take over should the need arise. There may be a brief delay (up to five seconds) while the second node takes over, but no data or transactions are lost.

On the other hand, ftServer systems duplicate all processing and I/O across both of its subsystems simultaneously. In essence, there are two computers doing the exact same thing at the exact same time, both acting as primary servers. If one of the subsystems fails, the remaining one continues to act as the primary server – only now by itself. There is no delay, since one subsystem is not “taking over” for another subsystem.

Are there any conditions associated with, or limitations of the automated local site recovery feature in ztC Edge?

The two nodes in a redundant ztC Edge system can be deployed in different physical locations, as long as the round trip latency in the network connectivity (a-links) between the nodes is below a 10 ms threshold for highly available workloads, and 2 ms for fault tolerant workloads. Meeting these conditions enables ztC Edge to deliver local site, or metro-area disaster recovery services. Stratus recommends that for nodes separated by more than 10 meters (or 33 feet), or for nodes bridged with external switches, a quorum service also be implemented.

I know Stratus also offers a software availability product called everRun. Is Stratus ztC Edge just everRun software running on an industrial PC?

No. Stratus ztC Edge, while it does leverage technology that is also in everRun, is a different solution. Both everRun and Stratus Redundant Linux (the OS in Stratus ztC Edge) utilize the same virtualization framework and availability layer. However, Stratus Redundant Linux further exposes features in ztC Edge hardware to offer dramatically simplified deployment, and more advanced, comprehensive system monitoring and management capabilities – more than that provided by the combination of everRun on industry standard hardware alone.

How rugged are ztC Edge’s nodes? What is their IP rating? What is their recommended operating temperature, and does this change with changes in altitude?

ztC Edge is IP40 rated, and features a durable, fan-less, solid state design with no moving parts. The ztC Edge 100i model can operate in temperatures ranging from -40 to 60 °C (-40 to 140 °F), when using DC power. The ztC Edge 110i model can operate in temperatures ranging from -20 to 55 °C (-4 to 131 °F), when using DC power. If the AC power supplies that are provided with the systems are used instead, the recommended operating temperature range changes to 0 to 50 °C (32 to 122 °F) for both models.

At higher altitudes, air is thinner and typically drier, which results in lower heat dissipation through air convection. As a result, the recommended operating temperature range at higher altitudes is reduced, because ztC Edge is a fan-less, convection cooled product. For example, at an altitude of 4200 meters (14,000 feet), the maximum ambient temperature should be kept below 35 °C (95 °F). For the recommended temperature ranges or ratings for your specific use case, please contact Stratus.

Does ztC Edge support Power over Ethernet? What is its inrush current?

No, ztC Edge does not currently support PoE. The maximum inrush current for both ztC Edge 100i and 110i systems is 20A. For additional technical specifications, please visit the ztC Edge product homepage on

How does IP addressing work with ztC Edge?

Each node in a redundant ztC Edge system has its own IP address, as does the system itself and each VM. Applications typically reside in VMs. Communications are handled by the system, with routing taking place to the VMs transparently, regardless of which node they are currently running on.