How Cloud Ninjas Slash EC2 Costs with Unused Reservations?

Jun 5 2014 | by Eran Abramson

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So you’ve done your homework, analyzed your AWS cost drivers and have added Reserved Instances to your AWS deployment portfolio, expecting your EC2 costs to drop. But just because the hourly rates are discounted for instances running as reserved, these savings are not always automatic. While in your AWS console RIs will always have a status of active, they may not technically be in use, as the instances the RIs were originally purchased for, might have been brought down. The net result is an unused RI that gives you zero value….but could potentially deliver major savings and ROI.

Before you go to your AWS console to find these unused reserved instances, you should be aware of the intricate detective work ahead:

  • You will need to look at all your reserved instances
  • Compare the number of RIs with actual running instances of the same profile (family, size, platform, AZ, etc.)
  • Check if there are less instances than RIs (again for specific family, size, platform, AZ) AND if there are less, you finally know you have unused RIs

This is already a bit of legwork and it gets much worse if you have tens or hundreds of RIs and instances. It will take an unbelievable amount of time with a high margin for error with so much data: type, region, size, availability zone, etc. Moreover, even if you are of the few that can attend such a task, it is not likely you will ever wish to do it a second time, or a third. But you must, or you will be missing out on RIs you have already paid the upfront fee for which can be potentially applied to matching On-Demand instances for immediate savings.

Easy Money with Cloudyn’s Unused Reserved Instances Reallocation Tool
A better alternative to tediously combing your AWS console is Cloudyn.

We continuously monitor across all your accounts and list any unused RIs, but we don’t stop there! We also provide optimization recommendation using these unused resources, such as where they may be relocated to or modified for reuse on matching instances.

Let’s look at a recent customer example where the Unused Reservation tool easily presented where additional savings were available, and how to take advantage of such potential.

The first screenshot shows 5 unused RIs, with all relevant details including their normalization factor and total points available for these instances (for potential modification purposes).

ec2 currently unused reservations 1 ri reallocation cloudyn

Also seen are different reallocation recommendations, which may include relocating from one availability zone to another or modification possibilities such as splitting or combining RIs per point availability and deployment need.

Getting excited yet? In case you aren’t yet, this basically shows:

  • Unused instances which cost you good money (i.e. the upfront payment already made) but are currently being wasted.
  • Where and how they may be optimally used, so you can get your money’s worth and reduce costs in other areas where on-demand instances are deployed.

So How Much Could This Actually Save Me?
In this customer scenario, without any additional payment to AWS, our client was able to significantly reduce part of his EC2 spend by over 70%. These tremendous savings were achieved simply by reallocating existing and already paid-for resources.

Based on our recommendations, our client saw the resource reallocating potential and made the following changes:
modifying reserved instances ec2 1 ri reallocation

    •  1 unused m1.medium RI was relocated  from us-west-2b to us-west-2a and applied to 1 m1.medium instance that had been running on-demand, reducing costs from $0.087/hour to $0.024*
    • 4 unused m1.medium RIs were modified to 8 m1.small RIs and applied to 8 matching instances that were running on-demand, reducing cost from $0.044/hour to $0.012/hour*
    • There were 10 RIs that were being utilized properly in us-west-2b, so those were left alone. AWS however requires you to re-confirm placement for all RIs of the type you are modifying

*EC2 pricing as of post’s publication date

Are you inspired and want to find if your deployment also has unused reserved instances? The first 20 days are on us, so why not kick off a free trial and we’ll be happy to help you slash your cloud costs.

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