Cloud migration presents a great opportunity to move applications to a more modern operating system (OS). In some cases, an OS update may be mandatory to meet the minimum supported cloud platform OS image versions. For example, Oracle Cloud currently offers Windows Server 2012 R2 Standard, Datacenter as the earliest available platform image level.

Migrating applications to cloud instances running an up-to-date version of Windows is the right approach from an ongoing support perspective and maximizes the flexibility and reliability of the cloud platform. However, certain legacy applications may have OS version limitations and this needs to be verified to confirm compatibility.

Cristie’s latest CloneManager® release offers the ability to perform a Windows OS upgrade in a sandbox test system within the cloud environment. This test system can then be checked for compatibility before committing the upgraded image to the target system.

Cristie VA Cloud migration with automatic Windows OS updates

CloneManager® provides the option of performing automatic Microsoft Windows OS updates following an initial image migration to the target system. If this option is selected a replication sandbox is created within the target system and a snapshot of the migrated image is taken to obtain a thin-provisioned copy-on-write layer that can accept changes and subsequently be used as a bootable test instance. Once booted, the upgrade procedure is initiated which will initiate the Microsoft OS upgrade process. Any OS licenses required following the upgrade process must then be applied by the user.

When system upgrades have completed, one of two things can happen; the system can be booted into the new operating system for validations to be run against applications on the system, or (if applicable) further upgrades can be run to bring the system up to the latest version. Automatic upgrades can be performed right through to the very latest Windows OS release, saving the labour overheads of a manual intervention. However, any application upgrades will need to be applied manually to the final image if required .

What can I do if my application has legacy OS dependencies?

Legacy applications that are OS-dependent or require a specific environment such as server and network hardware, databases, and storage resources can be problematic during a lift-and-shift cloud migration. Many cloud platforms offer a Bring Your Own Image (BYOI) capability which will allow certain legacy OS versions to run if the underlying platform infrastructure can support it. This will usually require the customer to supply a ‘cloud ready’ image that does not rely on unavailable 3rd party dependencies. If the lift-and-shift migration approach presents too many problems, you may be able to identify pieces of the application to transition to the cloud. This method, known as Application Evolution, allows users to migrate to the cloud in steps, rather than all at once, but this approach may cost more to operate.

Another approach known as Application Re-Architecting breaks down applications and then rebuilds them in a more scalable, modern design. With this scenario you are not completely starting from scratch, but merely eliminating any code that constrains your ability to migrate to a modern OS version, while preserving and potentially enhancing business-relevant functionality in the process. Application re-Architecting is best for legacy applications that are business-critical and provide competitive differentiation, as completely reworking an application for the cloud can be a big undertaking.

In summary

The automatic Windows upgrade feature introduced with the Cristie Software VA 4.5.1 release offers a hybrid lift-and-shift cloud migration environment that greatly simplifies legacy application testing and reduces the time and effort required when Windows OS updates are required to meet cloud platform requirements. CloneManager® and the Cristie VA support cloud migration to many platforms including Oracle Cloud, Azure and AWS for both physical servers, VMs, and containerized applications. Visit the CloneManager® product pages or contact the Cristie Software team for more information on system replication & migration.