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INSIGHTS / Articles

What are the Challenges of Testing a Data Centre Migration?

 13 Jan 2016 
INSIGHTS / Articles

What are the Challenges of Testing a Data Centre Migration?

 13 Jan 2016 
What is a Data Centre?

The Data Centre is the heart of any organisation - a complex, integrated array of equipment, software and data that drives the business and powers every aspect of its operations.

Recent trends show that Data Centre Migration tops the list of key projects for most organisations to meet their future business requirements and keep up with technology. These projects are also undertaken for better financial control as the Data Centre is one of the most financially concentrated assets of any organisation. Typically, the CFO views it as a cost, while the CIO considers it as a business challenge.

Elements of a Data Centre

  • Applications


  • Operating Systems


  • Mainframe, Servers


  • Data, Storage


  • WAN, LAN, Network

Importance of Testing

For those without experience in this domain, it may appear as if moving/building infrastructure at a target Data Centre is predominantly about hardware infrastructure. However, it’s all about the applications. Business runs on the applications that reside in a Data Centre. The goal is to ensure that there are no impacts to the functionality of the applications and to minimise the downtime of business-critical applications. It is absolutely imperative that a proper test strategy is developed along with the migration strategy and adequate funds and resources are allocated.

Types of Migration

Migration of IT infrastructure generally falls into four categories; Physical to Physical (P2P), Physical to Virtual (P2V), Virtual to Virtual (V2V) and Physical/Virtual to Transformation.

Physical to Physical (P2P)

P2P is the simplest form of migration where physical devices are lifted and shifted to the new location.

  • No changes to hardware configuration
  • No changes to OS version
  • No changes to application version

Physical to Virtual (P2V)

In P2V, Physical server’s Operating system (OS), application and data are migrated to a virtual machine on a virtualised platform.

  • Changes to hardware configuration
  • No changes to OS version
  • No changes to application version

Virtual to Virtual (V2V)

In V2V, Operating system (OS), application and data are migrated from one virtual machine to another virtual machine.

  • Changes to hardware configuration
  • No changes to OS version
  • No changes to application version

Physical/Virtual to Transformation

In these migrations OS, application and data are migrated from either Physical or Virtual machine to an upgraded OS to improve efficiency and flexibility.

  • Changes to hardware configuration
  • Changes to OS version/cross-platforming
  • No changes to application version

Each migration type has its own distinct advantages and disadvantages. It’s often seen that more than one type of migration is chosen by the organisation. The decision is mainly driven by the complexity of the migration, criticality of the application, return on investment, duration and allowable downtime.

What to Test?

The testing effort is focussed on validating all infrastructure components, application operability and functionality. Regardless of type of migration that the organisation may choose, areas mentioned above must be tested thoroughly. The table below gives an overview of what is typically covered under each area.

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Infrastructure Testing

  • Operating System, Network, OSS, storage and back up
  • Done by the relevant technical resources

 

Operational Testing

  • Application components, configuration and connectivity
  • Application health and sanity checks
  • Done by the Operation team

 

Application Testing

  • Functional and Non functional testing
  • Typically includes E2E business scenarios
  • Done by the business users and/or professional testers
Test Strategy/Approach

In Data Centre Migration projects, the aim of testing is not to find defects in the software but to ensure that applications are functioning ‘as is’ and there is no impact to the business. Therefore, it’s extremely important to develop a fit for purpose test approach based on the following principles:

  • Perform pre-migration testing before infrastructure equipment is migrated in order to form a ‘baseline’ on infrastructure, applications operability, functionality and performance. Any issues found during pre-migration testing are resolved or accepted by the business. The same test cases are executed post migration and results are compared with the baseline. Pre-migration testing offers best insurance against any production breakage.
     
  • Ensure redundancy – Often mission critical applications are designed to have redundancy i.e. Server level, site level. In these cases, it is important to test the failover scenarios to ensure that application redundancy is maintained.
     
  • Understand the application architecture – upstream applications, downstream applications and any dependencies. Applications residing in non-production environments may not have production-like connectivity. As such, the test approach may slightly differ for production and non-production environments.
     
  • Leverage cost and time efficiencies by:
    → Using existing business as usual (BAU) validation elements.
    → Adopting a risk based approach to testing by collaborating with the business specialists to identify the highly valued, critical business components/functionality. Based on this information prioritisation of testing can be agreed. Test coverage decisions can be made on the basis of acceptable risks using pragmatic judgement.
    → Utilising the existing knowledge base of the organisation’s test and business experts and, where possible, reusing the test cases that are already in place.
     
  • Employ early planning and upfront stakeholder agreement by:
    → Developing test planning documentation, including detailed application test entry, exit and acceptance criteria for each application/migration group.
    → Socialising test plans with all stakeholders.
     
  • Adopt continuous process improvement (CPI) to continually build upon efficiencies in the test process and to increase the overall quality for the program of work.
     
  • Embrace a collaborative testing effort between applications and infrastructure to facilitate early detection of issues. Follow a test approach that matches the type of migration. For example; In ‘Lift and Shift’ type migration, testing is done pre- and post-migration. Where in ‘Physical/Virtual to Transformation’ type migration, infrastructure equipment and applications are available before the actual cutover/migration with testing occurring at that stage. The table below gives an overview of testing approach for different types of migration.

Example of High Level Test Approach

P2P, P2V, V2V

Infrastructure Testing

Operational Testing

Business Application Testing

Pre-Migration (Baseline)

Post-Migration

Physical/Virtual to Transformation

Infrastructure Testing

Operational Testing

Business Application Testing

Pre-Migration (Baseline)

 

Transformation*

Post-Migration

 

Conclusion

Data Centre migration is not merely migrating hardware infrastructure but keeping the business intact by ensuring that applications are functioning as per normal with no degradation in performance and minimal down time. Effective testing is of critical importance to realising successful migration and, as demand for Data Centre migration and expansion increases, it is paramount that a risk based test strategy is developed along with migration strategy.

Vishal Thaker

Principal Consultant

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