Viability assessment – RAID log

Good design is good business - Thomas J. Watson

In IBM’s method Team Solution Design, Viability Assessment is intended to record the Risks, Assumptions, Issues and Dependencies (hence the acronym RAID).  
In other words, we document the findings, risks and recommendations as a result of Viability Assessment. A finding (and the associated risks) could be anything that is likely to influence the delivery of the solution such as:

• The ability to meet the solutions requirements. 
• The availability of the right skills. 
• The stakeholder acceptance of the technical elements of the proposed solution. 
• The ability to meet the schedule and budgetary constraints defined for the solution. 
• Lack of reusable elements in the solution. 

Usual an ISSUE is closed / removed in viability assessment process by raising it as a RISK or as a Change request.

The result can be documented as an excel file which can be sorted and filtered on needs. 
This approach helps the reader to understand the common pitfalls of designing VMware vSphere based solutions, as well to cross-check solution activities and design elements that must considered in order to avoid risks.

Now let’s give some examples: 

• Risk:

R/A/I/D	Risk
R/A/I/D ID	RAIDnnn
R/A/I/D Name	Having too many clusters
Description	Specific requirements force to have multiple clusters with very few workloads.
Priority (H/M/L)	M
Impact (H/M/L)	H
Raised by
Responsibility / Owner
Mitigations / Comments	In typical virtual environments, workloads should have different profiles and be as mixed as possible to yield the best consolidation ratios, and thus to minimize the number of hosts. Make sure you have clear defined requirements for having multiple clusters and that everybody understands the consequences (more hosts = more costs)
Review date
Closed date

• Assumption:

R/A/I/D	Assumption
R/A/I/D ID	RAIDnnn
R/A/I/D Name	Host profiles
Description	The solution uses host profiles which assume all host hardware is the same.
Priority (H/M/L)	L
Impact (H/M/L)	L
Raised by
Responsibility / Owner
Mitigations / Comments	Using host profiles might create issues if hardware configuration (PCI allocation) or cabling and connections to network switches and storage devices are not consistent. Precautions during build phase of new hosts. If configuration not consistent, use separately host profile for each host type.
Review date
Closed date

• Dependency:

R/A/I/D	Dependency
R/A/I/D ID	RAIDnnn
R/A/I/D Name	VMware tools
Description	Use only supported guest OS and have up to date VMware tools version running. Many features, as well the performance are depending on VMware tools.
Priority (H/M/L)	L
Impact (H/M/L)	M
Raised by
Responsibility / Owner
Mitigations / Comments	Most common OS used are supported. That means also VMware tools can be installed. Having VMware tools up to date is a must.
Review date
Closed date