Please note that the guide below should only be considered a quick reference for people already experienced with enterprise infrastructure design who are studying for a VCAP Design exam. This is in no way an alternative for proper training such as VMware CAL, TOGAF, etc.
1: design process⌗
- Assess - this is where the design begins with requirements and other data gathering from the customer; you should identify business objectives, key stakeholders and scope of the engagement. Conceptual designs, current state reports are common deliverables in this phase.
- Design - an iterative process consisting of multiple cycles of writing design drafts, reviewing designs with stakeholders and interviewing key people to better understand their goals. By the end of this phase, all design blueprints should be signed-off (conceptual design, logical design, and physical design).
- Deploy - installation and configuration of the solution as per the design; often also includes changes to the design caused by unexpected complications or additional requirements. Configuration and installation workbooks are usually produced as part of the deployment,
- Validate - after the build, the solution has to be verified to make sure it meets the business objectives and goals; this is also when the customer can learn the mechanics of the solution. A successful validation should be documented in validation reports and testing results (DR, performance, etc)
2: three-step design model⌗
- Conceptual Design - high-level design based on the information gathered during the assessment phase; conceptual design should include business requirements, assumptions, constraints and risks along with design decisions and justifications.
- Logical Design - takes the points from a conceptual design and maps them to solution components; it defines how to arrange and use components and features of the infrastructure to satisfy the business requirements. Important to note that the logical design does not delve into details about each of the components - that’s where the physical design comes in.
- Physical Design - the lowest level design which maps everything from conceptual and logical designs to the actual hardware and software, and includes the configuration details needed to build the solution. This is the design which will primarily used by the engineers in charge of implementing the design and configuring the solution.
3: design requirements, assumptions, constrains and risks⌗
- Requirements - describe what should be achieved in the project and what the solution needs to look like; the requirements must come from key business stakeholders and the ultimate goal of the design is to achieve each and every single one of them.
- Assumptions - conditions impacting the design which are believed to be true but must be confirmed before finalizing the design.
- Constraints - conditions that provide boundaries to the design; while requirements allow for multiple options and to make a design decision, constraints leave no room for changes and force a design decision without any input from a designer.
- Risks - factors which might have a negative impact on the design; before finalizing the design, all risks should be mitigated - this can be achieved by one of risk mitigation actions (accept, avoid, control, transfer, or monitor)
4: functional vs non-functional requirements⌗
- Functional Requirements - describe what the system or solution must do; these also specify functions that the system or solution must perform. Common examples of functional requirements include:
- Business Rules
- Administrative Functions
- Audit tracking
- Legal and regulatory requirements
- Non-functional Requirements - describe the quality of the system or solution; these specify how the system or solution should work in order to support the functional business requirements. Generally, we can split non-functional requirements into the five categories below:
- Availability - redundancy levels, single point of failure, class of nines
- Manageability - lifecycle management, scalability, capacity planning
- Performance - throughput, latency, transactions/operations per second
- Recoverability - RTO, RPO, MTD, restore process and methodologies
- Security - government regulations, industry standards, penetration testing standards