The Dell Validated Design for Energy Edge includes single-node, 2-node, and 3+ node cluster options, depending on workload needs and HA requirements. A single-node configuration provides the necessary hardware to run multiple application virtual machines (VMs) but without HA and will incur downtime when host failures happen. The 2-node and 3+ node configurations provide the necessary redundancy to offer a highly available processing environment with the 3+ node option providing both infrastructure and workload HA. See the System Design chapter for a complete list of components and the Bill of Materials for hardware specifications. For vSphere documentation, see the VMware vSphere Documentation.
Resiliency of the ISV application stack on VMware
As described earlier, there are several components involved in the solution, and all of them offer varying degrees of resiliency.
ISV application services are automatically started when the VM fails over or migrates to another node in the VMware cluster, making the entire stack ready to use without user intervention. As user connectivity relies on access to the web services—other than a momentary glitch—there is no impact to the users.
Role-based HA management for devices, users, and applications
ISV applications may not offer the role-based service level management needed to ensure that a certain set of mission-critical applications, users, and devices have higher availability compared to other noncritical users. Role-based HA management is important to ensure that high-priority applications remain available and continue to perform. This requires application deployment with proper understanding of the application, user load, connected devices, and priorities.
There are several ways to address the needs for role-based HA management:
- Based on the prioritized grouping of the ISV application components, a separate set of VMs and database VMs can be used for deployment. Such physical separation allows configuration of a different set of policies to ensure higher availability. VMware DRS allows fully automated, partially automated, and manual placement for load balancing and resource scheduling. VMware HA offers host rules to keep a user-defined set of VMs together. ISV application VMs can be configured with specific host rules to ensure consistency of performance and availability across all application components. This separation of the application stack also allows the use of independent database services and storage devices with additional policies.
- Such role-based configurations assist in identifying the requirements for additional VMware ECS clusters, ISV applications, and related components.
- Similarly, other policies like security, alerts and monitoring, database snapshots, backup and recovery can also be employed differently when considering role-based availability of ISV applications.
RPO and RTO management
For 24/7 industrial environments, the ability to quickly troubleshoot a failure, and more importantly, recover from a failure situation, are key considerations. Different users, applications, and devices can have a different Recovery Point Objective (RPO)—which brings the application state to the last good state for continued operations—and Recovery Time Objective (RTO). RTO is the time it takes to bring the entire application stack to the last good state. ISV applications depend on continuous availability of database services, and various backup and recovery options are available to ensure availability of the application stack. Thus, ISV applications running on VMware help to manage and improve RPO and RTO.
Aggregating data sources and supporting multiple use cases at scale
Edge applications aggregate data from a diverse set of sensors, devices, and gateways that support various network topologies and use different protocols for northbound traffic to edge systems. ISV applications support a large set of such protocols and communication channels. It is common to have multiple layers of gateways supporting a large set of sensors. ISV applications support many protocols for northbound traffic and can communicate with multiple application instances. By deploying multiple instances, and aggregating and storing data from diverse data sources, users can realize HA and also provide an additional set of services from multiple instances.
For example, one ISV application instance can be used for analytics and predictive maintenance, whereas another can be used for reporting overall health of the system and time series data.
Isolation and multitenant network management
Many edge devices provide multiple physical interfaces to connect to multiple northbound IP addresses that support various ISV applications. VMware infrastructure and network switches support multiple network interfaces. Such redundancies in the network configuration offer HA, and if any network paths go down, operations are not impacted. Such networks can be configured with independent VLANs to isolate traffic for multitenant environments, improving overall availability and allowing effective noisy neighbor management.