Friday 14 October 2016

VCAP6-DCV Design Objective 2.3

We already had a detailed discussion about VCAP6 - DCV Design exam, where we discussed about the Path we need to follow and what are the objectives that we need to take care, If in case you missed it here is the link for your reference Kick Start Your Journey Towards VCAP6-DCV Design.

We have also seen VCAP6-DCV Design Objective 1.1, VCAP6-DCV Design Objective 1.2 and VCAP6-DCV Design Objective 1.3 in which we discussed about Business and Application Requirements,Risks,Constraints, Assumptions and also discussed how to map the business requirements into VMware vSphere Logical Design and also talked about mapping service dependinces here are the links for your reference in case you missed it VCAP6-DCV Design Objective 1.1VCAP6-DCV Design Objective 1.2 , VCAP6-DCV Design Objective 1.3 , VCAP6-DCV Design Objective 2.1VCAP6-DCV Design Objective 2.2

Objective 2.3 – Build Availability Requirements into a vSphere 6 Logical Design

Skills and Abilities
  • Evaluate which logical availability services can be used with a given vSphere solution.
  • Differentiate infrastructure qualities related to availability.
  • Describe the concept of redundancy and the risks associated with single points of failure
  • Explain class of nines methodology
  • Determine availability component of service level agreements (SLAs) and service level management processes
  • Determine potential availability solutions for a logical design based on customer requirements.
  • Create an availability plan, including maintenance processes.
  • Balance availability requirements with other infrastructure qualities.
  • Analyze a vSphere design and determine possible single points of failure.
How to Prepare
Now that we have seen what are the skill's and abilities required towards the preparation of VCAP6-DCV Design Objective 2.3 it's time to proceed further and work towards the content available in the above mentioned Links and understand how they help us in building availability requirements into vSphere 6 logical Design.

I Still remember one of the class I delivered for VMware vSphere Design & Deploy 6 fast track course (which helps audience prepare for VCAP6-DCV Design and VCAP6-DCV Deploy exam).

During the class we had an awesome discussion about gathering the availability requirements and how these requirements plays a Vital role in your VMware vSphere Design.

Let's start with High Availability which is one of the key feature in VMware vSphere and helps provide us protection against various failures including (Application Failure, Guest OS Failure, Network Isolation, Host Failure and Datastore related issues).

Image Source VMware
Before we talk about how VMware vSphere High Availability helps us in providing the protection against various failure let's spend some time in understanding planned and unplanned downtime though both are downtimes and will hamper the production machines any how but understanding them better can help us in reducing them and improving the service level agreements.

Planned Downtime - Whether it is hardware maintenance, server migration, and firmware updates all require downtime for physical servers

With VMware vSphere we can reduce the planned downtime by migrating our workloads to different ESXi host without downtime or service disruption.

Unplanned Downtime - Various VMware vSphere capabilities including shared storage.
(we can eliminate single points of failure by storing virtual machine files on shared storage.

NIC Teaming which provide tolerance of individual network card failures.

Coming back to VMware vSphere High Availability which provides us the protection against various failures as mentioned above but whether we need to use these features or not again is an important question that need to be addressed?

My design requirements includes the application requirements will help me answer this question maybe the client for whom I am preparing this design doesn't need the VM and Application level monitoring as they are using third party tool for the same.

But they are looking for protection against host level failures so as the Virtual Machines can be restarted on a different ESXi host with minimal amount of downtime, yes downtime is still there as the affected Virtual Machines would be restarted on different ESXi hosts.

Another requirement may fall in the Design where in they have some mission critical virtual machines on which we can't afford any downtime being a solution architect we can propose them another important feature available in VMware vSphere i.e Fault Tolerance and how FT provides us protection without dataloss and TCP/IP loss. If in case you are new with how FT works here is a quick link for your reference Back to Basics - Part 10 Fault Tolerance
Another beautiful white paper which talks about how we can Protect our Business with Automated Business Continuity Solutions by overcoming various cost and complexity challenges and how we can Extend our Virtualization Investment to Achieve High Availability directly contribute in achieving our objective 2.3.

Key Note- It's always considered worth when working with the Design to consider VMware Design Best Practices which talks about Host Placement, Auto Deploy,VMware vCenter Server Availability considerations, Networking Design Considerations (Redundancy, NIC Teaming, Load Balancing Policies to be used), Storage Considerations.

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