VCAP5-DCD Objective 2.2 – Map Service Dependencies

Knowledge

• Identify basic service dependencies for infrastructure and application services.

This will be done during the current state analysis, There are products that will help identify application dependencies like VMware vCenter Application Discover Manager or even VMware Infrastructure Navigator can highlight dependencies.

For example a 3 tier application Web Server- Application Server – Database Server.

Application server is a dependency of the web server and the database server is a dependency of the application server, then AD would be a dependency for all 3 for user authentication.

There is 3 discovery methods:

• Active – uses common network protocols to remotely query servers to get a picture of the servers and what they are listening for.
• Passive – provides more relationship data than the above active discovery, basically listens and samples network traffic to see what is talking to what and on what port.
• Analytics – complements the above 2 by performing deep analysis of observed traffic

Skills and Abilities

• Document service relationships and dependencies (Entity Relationship Diagrams)

This determines which entities are related, Majority of this discover would be done during a current state analysis, you then use this information to create down and up stream relationships. Relationships can be defined in the following terms:

• Runs on / Runs
• Depends on / Used by
• Contains / Contained by
• Hosts / Hosted by

• Identify interfaces to existing business processes and define new business processes

This basically depends on what is discovered, Say it was discovered all MSCS virtuals must be moved off the current cluster and onto a dedicated ESXi cluster, so that the SCSI LUN limit isn’t reached on the existing production cluster. Operations Would need to be notified that there is a new process when trouble shooting these boxes and that they are not residing on different infrastructure  Design would have to have a new process and point any MSCS virtuals to the newly created cluster, etc.

• Given a scenario, identify logical components that have dependencies on certain services.

Take for example this website which runs on ISS which is running on a Windows Server which is running on a VMware Cluster.

• Include service dependencies in a vSphere 5 logical design.

Remember Logical design has not got much detail in it, SO if you find a dependency on a server or service include it in the logical design

• Analyze services to identify upstream and downstream service dependencies.

Take the image above, what happens down stream effects everything upstream, So for example, if the guest OS of Microsoft Windows Blue Screens then the IIS service is affects which in turn effects the website. But service upstream  wont effect downstream so if IIS Service fails  only the website is effected but guest OS and below are functioning normal.

• Having navigated logical components and their interdependencies, make decisions based upon all service relationships.

After you have worked out the relation ships they type of decisions can be made to say make applications into vApps so you have web,application and database sitting together in a single logical unit.