This blog post covers objective 2.2 (Map service dependencies) of the VCAP6.5-DCV Design exam. It is based on the VMware Certified Advanced Professional 6.5 in Data Center Virtualization Design (3V0-624) Exam Preparation Guide (last update August 2017).
The necessary skills and abilities are documented in the exam prep guide for the older VCAP6-DCV Design exam (3V0-622). I think they also apply to the current version of the exam:
- Evaluate dependencies for infrastructure and application services that will be included in a vSphere design
- Create Entity Relationship Diagrams that map service relationships and dependencies
- Analyze interfaces to be used with new and existing business processes
- Determine service dependencies for logical components
- Include service dependencies in a vSphere 6.x Logical Design
- Analyze services to identify upstream and downstream service dependencies
- Navigate logical components and their interdependencies and make decisions based upon all service relationships
Let’s start with the first topic of this objective.
Evaluate dependencies for infrastructure and application services that will be included in a vSphere design
This topic covers two different parts of our vSphere design:
- infrastructure, and
- application services
You should clarify what components of your design depend on each other, or if they depend on components, that are not part of your design. VMware HA needs a shared Storage, or VMware ESXi needs NTP and DNS to work properly.
The same applies to the application services (or applications) that are part of your design. What dependencies do they have. Imagine a three-tier application with database, application logic and web frontend.
You must be able to identify and describe these dependencies.
Create Entity Relationship Diagrams that map service relationships and dependencies
If you are able to identify and describe the dependencies, you also must be able to create a Entity Relationship Diagrams (ER-Diagram) to visualize these dependencies.
Do your homework and try to identify these dependencies at the beginning. Tools like the vRealize Infrastructure Navigator can help you to identify them.
Analyze interfaces to be used with new and existing business processes
It is pretty important to understand how systems interact. To gain this knowledge, you have to analyze the interfaces of business processes. This doesn’t mean that you have to click through ERP applications, but you should get familiar with how processes are tight together.
Determine service dependencies for logical components
You also have to identify the service dependencies for the logical components in your design. You can use tools like vRealize Operations Manager or the Infrastructure Navigator to get the necessary information.
Include service dependencies in a vSphere 6.x Logical Design
The identified service dependencies have to be included into the logical design. This is a pretty important step and you should pay it the necessary attention. Tables and ER diagrams will help you at this step.
Analyze services to identify upstream and downstream service dependencies
An upstream service is a service, which is mandatory for another service, because it relies on it. Downstream services need upstream services to work properly. For example: DNS is an upstream service for Active Directory.
The understanding of up- and downstream services is important for things like startup/ shutdown plans.
Navigate logical components and their interdependencies and make decisions based upon all service relationships
You should visualize the service dependencies. This will help you to evaluate the impact if a service fails or how service are interact with each other.
Most of the topics in this objective overlap. Quite basic everything is about the understanding how things are connected and interact. This will help you to get a better understanding of dependencies and what services are crucial for the business or your solution.
Think again on DNS. No one of us will ever build a solution with a single DNS server, because nearly everything will melt down if DNS is not available. DNS is a perfect example for an upstream service.