Migration Insights - ISSUE 1 - REHOST

Services, techniques and use-cases for adopting cloud services and transforming information technology services.


The first in a series of posts for 2020 where the junkshon team will provide insights as to how to migrate services to the cloud. The team has performed many migrations, data centre transformation and applications modernisation and deployment programmes for customers globally.


The topics will range from:


  • how to perform an efficient discovery

  • building your landing zone to meet your workload requirements

  • using the latest cloud services to accelerate your transformation

  • setting up your delivery teams for success selecting the best migration options managing a programme efficiently and at the lowest possible price point and risk level using technology to help manage the migration/modernisation programme

  • developing your new operating model


And lots more.


In our first issue, we are looking at the migration treatment Re-host, one of the 6Rs of application migration.


The industry definitions for each of the 6Rs are described below.


  • Rehost. Redeploy an application component to another physical, virtual or cloud infrastructure without recompiling, altering the application code, or modifying features and functions.

  • Replatform. Migrate an application component to a new runtime platform. Make minimal changes to code to adapt to the new platform, but don’t change the code structure or the features and functions it provides.

  • Refactor. Restructure and optimize existing code without changing its external behaviour to remove technical debt and to improve the component’s features and structure.

  • Rearchitect. Materially alter the application code so you can shift it to a new application architecture and fully exploit new and better capabilities of the application platform.

  • Rebuild. Rebuild or rewrite the application component from scratch while preserving its scope and specifications.

  • Replace/RePurchase. Eliminate the former application component altogether and replace it, taking new requirements and needs into account.


Re-hosting


Overview

The Re-host treatment also referred to as lift and shift, is a workload migration method that involves moving the application and operating system to the new target landing zone.

Re-hosting entails the as-is move of the existing applications and associated services to either a new virtual machine solution or physical server. These as-is applications can be already virtualised or running on the non-virtualised infrastructure.


The best candidates for re-hosting are:


  • applications that have an active roadmap from the 3rd party application vendor or the internal support applications team.

  • applications identified as maintain only from the discovery assessment phase and need to be moved at a minimal cost.


Re-hosting your applications typically is the lower risk method for migrating workloads between data centres or to the cloud as the applications in scope for re-host are the ones with a high degree of cloud compatibility and hence minimum cost and effort to migrate.

The primary benefit of the re-hosting approach is the ability to reduce infrastructure debt and operating costs. This approach will also allow organisations to learn about managing services in the cloud and develop the required skills within the business.


Approach


The re-host approach takes an image copy of the source system and migrates the image to a new target virtual machine running in the cloud.


Some companies will tell you that this approach requires no change to the operating system, agent ware or application code. Our experience at junkshon is that while re-hosting a server does have minimal impact on the operating system and application, there are times when changes are required to make sure the application runs correctly on the cloud platform.


Re-host Model

Some of the key change considerations when performing a re-host are:


  • Can you retire and deinstall existing monitoring agents as you move to the cloud? Many of the cloud providers offer monitoring services as part of their service control plane.

  • Will your Software distribution service and patching tools work inside the new virtual private cloud environment.

  • Sometimes the IP address will change as part of the migration process, and this may mean that application configuration files or even source code will need to be updated.

  • When migrating to the cloud using a re-host model, it is essential to assess the cloud network services and understand and test your applications against components like Load Balancers, SSL acceleration devices and DNS services.


Other non-technical considerations include:


  • Can the software you are currently using be operated on the target cloud platform? Even in today's I.T. landscape, some software vendors still have licensing policies that are not aligned with new cloud computing models.

  • Can you operate the new cloud platform? If you manage the cloud like a traditional estate, you will not gain the benefits of cloud management approaches, e.g. infrastructure as code.


How can junkshon help?

We can provide rapid estate analysis and advisory and build your mass migration strategy and plan. We understand in detail what it takes to migrate workloads to the public cloud or between data centres.


Check out our strategy package:

https://www.junkshon.com/migration-strategy

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