A Word on Size Flexible RIs

The Cloudologist
May 16, 2017
3 minute read

The content in this blog is outdated and we cannot reliably say it is still accurate with the speed in which the cloud industry moves. But don’t worry—below are more recent, up-to-date blogs.

AWS Rightsizing For Cost Optimization

The 5 Best Ways To Reduce AWS Instance Cost

The Ultimate Guide To Amazon EC2 Reserved Instances

As a follow-up to my piece on the struggles of managing a hybrid cloud environment, I thought it would be a nice change of pace to go from talking about something all-too-familiar to something nobody totally understands: AWS Reserved Instances.

I’m joking..kind of. RIs are excellent in many ways -- they provide opportunity for significant discount on your compute costs, IF (and that’s a big if) you understand and know how to manage them. More on that here. Now, AWS recently announced Size Flexible Reserved Instances...AKA Size Flex RIs.

(Pun intended.)

In a blog post on the topic, Jeff Barr writes:

“Effective March 1, your existing Regional RIs are even more flexible! All Regional Linux/UNIX RIs with shared tenancy now apply to all sizes of instances within an instance family and AWS region, even if you are using them across multiple accounts via Consolidated Billing. This will further reduce the time that you spend managing your RIs and will let you be even more creative and innovative with your use of compute resources.”

In a nutshell, RIs are now more compelling and more confusing.

(Sidenote: In this discussion, to keep things simple, I will only discuss Standard Reservation types. Convertible Reservations offer even greater opportunities for increased flexibility, although they require a three year commitment. For the scoop on Convertible RIs, check out this blog post.)

Back in the day, buying an RI meant commitment. To a lot of things -- including instance type, availability zone, and operating system, among others. Then, like so much in the tech industry (watching television, online shopping, hailing a cab), RIs morphed to provide greater convenience and flexibility to the end user. Now you only have to commit to an OS, instance family, and a Region to get the benefit of RIs.

Size Flex RIs give commitment phobes a break by ameliorating concerns around usage or lock in. But they also make the RI purchasing process more labor intensive because now it’s an even tougher job to determine which reservations you should buy. In response to this new development, the CloudHealth engineers adapted the platform to provide recommendations that take into account instance usage and float across instance types and locations, so you can effectively manage the entire RI lifecycle, including Size Flexibility.

On a macro level, Size Flex RIs carry interesting industry implications. The cloud wars have made headlines for months -- watching AWS, Google and Microsoft duke it out on the world stage is can’t-miss, nail biting stuff (at least for a cloud nerd like myself). Although AWS is the undisputed market leader, the idea of a Size Flexible World feels like a distinctly Google-like strategy. Everyone’s favorite search engine company made a similar move at Google Cloud Next, announcing a completely flexible offering with no up-front financial commitment.

Cloudologist take: The idea of sustained use discounts carries obvious customer appeal, and it’s nice to see that the cloud giants are factoring this into their product strategy. In this technology battleground, flexibility is clearly today’s weapon of choice. Let’s see what hits next.