Cloud Updates Migration Optimization Tips

Understanding Size Flexible Azure Reserved Virtual Machine Instances

Recently, Microsoft released instance size flexibility for Azure Reserved Virtual Machine (VM) Instances. If you are a reservation beginner, you may not have a full understanding of the impact of this announcement. Let’s break it down.


What are size flexible Azure RIs?

Instance size flexibility for Azure Reserved VM Instances, also referred to as size flexible RIs, enable you to apply reservation discounts to different VM sizes in the same size series group. For example, if you purchased one Reserved VM Instance for a E16s v3, the reservation will apply to the other sizes in the E2s-64s v3 series group (e.g. E2s v3, E4s v3, etc), based on the size ratio calculated by Microsoft.

This new attribute applies to new and previously purchased reservations with a shared scope. Reservations with a single scope can also benefit from instance size flexibility, however this will need to be enabled from your Microsoft reservation configuration. To make things even better, the cost benefit applies regardless of the operating system (e.g. Windows, Linux, etc.).

How size flexible Azure RIs make an impact

Previously, Reserved VM Instances required a one or three year upfront commitment for a specific VM size, scope, and region, among other attributes. Now, Microsoft is simplifying their reservation offering because the cost benefit seamlessly applies to other VMs within the same VM group and region, without the hassle of exchanging or cancelling. Size flexible RIs are designed to ease commitment concerns and give you greater flexibility, however they can cause confusion in which reservations should be purchased from the get go.

It’s important to note that while this is new functionality for Microsoft, AWS released size flexible RIs in 2017. The leading cloud providers are in a constant battle as Microsoft starts to close the functionality gap.

Master RI management with CloudHealth

To ensure a positive return on your investment, RIs must be tailored to meet your specific business needs and goals, and therefore require continuous monitoring and management. Instance size flexibility alleviates challenges associated with exchanging and cancelling, however, you may still get overwhelmed by purchasing and utilizing reservations to their fullest potential.

CloudHealth takes the hassle out of RI management with support for size flexible Azure Reserved VM Instances. You can save time modeling purchases with the CloudHealth Virtual Machine RI Optimizer, which provides your potential savings and more importantly, the payback period. Within the Virtual Machine RI Optimizer, we have added a configuration checkbox for size flexibility. Post purchase, you can leverage CloudHealth cost and usage reports to amortize reservations, determine if they are underutilized, and identify opportunities to purchase additional reservations.

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