Comparing AWS Reserved Instances vs. Google Committed Use Discounts

Comparing AWS Reserved Instances Vs. Google Committed Use Discounts

CloudHealth Tech Staff
Jan. 11, 2019
7 minute read

A price comparison matching AWS Reserved Instances vs. Google Committed Use Discounts is not a sound basis for choosing one Cloud Service provider above another. We explain why and provide examples of what you should look for when evaluating long-term discounts for cloud services.

AWS' Reserved Instances and Google's Committed Use Discounts both provide an opportunity to reduce cloud costs by committing to a level of service for a predetermined period. The two cloud service providers respectively advertise discounts of up to 75 percent and 57 percent on pay-as-you-go prices depending on the length of the commitment and—in the case of AWS—how much you pay upfront.

However, comparing AWS Reserved Instances vs. Google Committed Use Discounts on the percentage of the discounts does not give a clear picture of which option may be best suited to your needs. Whereas the maximum discount advertised by AWS may look appealing, it is only attainable if you forgo the flexibility of Convertible Reserved Instances.


The difficulty in compiling an AWS RI vs Google CUD price comparison

If you have ever been tempted to compile a price comparison matching AWS Reserved Instances vs. Google Committed Use Discounts, you will likely appreciate the difficulty involved due to the number of variables. Although both discount programs are similar inasmuch as they offer discounts in return for one-year and three-year commitments, there are many ways in which they differ. For example:

  • AWS offers the options to pay all,partially, or nothing upfront in return for a larger discount.
  • Google Cloud Platform offers the opportunity to apply discounts to customized instances.
  • AWS offers additional volume discounts to businesses that spend >$500,000 per year.
  • Google's discounts are restricted to instances with between 0.9GB and 6.5GB memory per CPU.
  • AWS discounts can be applied to Standard or Convertible Reserved Instances.
  • Google Committed Use Discounts only apply to instances in the same family.
  • The two cloud service providers charge differently for dedicated “sole-tenancy” instances.
  • AWS limits businesses to purchase 80 Reserved Instances per month (20 per AZ plus 20 per Region).
  • There is no maximum number of Google instances that qualify for a Committed Use Discount.
  • AWS offers Reserved Instances with guaranteed capacity when an Availability Zone is specified.

What is also worth pointing out is that once you have fully loaded an AWS Reserved Instance reservation, any remaining instances you deploy on AWS are charged at the full On-Demand rate. With Google Cloud Platform, any instances you run above your Committed Use commitment may qualify for Sustained Use Discounts. Obviously if you had a lot of On-Demand AWS instances running long term, you would purchase more Reserved Instances; but in the short term Google Cloud Platform may be the better option.

Learn more about comparing the services of the big three cloud providers (AWS, Azure, GCP) in our ebook here. 

A like-for-like AWS Reserved Instances vs. Google Committed Use Discounts comparison

In order to conduct a like-for-like AWS Reserved Instances vs. Google Committed Use Discounts comparison we have selected regional, standard AWS instances and compared their Reserved Instance (RI) prices per month (without any upfront payments being applied) against similar Google instances after a Committed Use Discount (CUD) has been applied. Prices are expressed in U.S. dollars per month.

Like-for-Like AWS Reserved Instances vs. Google Committed Use Discounts Comparison
AWS 1 Year RI 3 Years RI GCP 1 Year CUD 3 Years CUD
m5.xlarge $89.79 $62.05 n1-standard-4 $87.38 $62.42
m5.2xlarge $178.85 $123.37 n1-standard- 8 $174.75 $124.84
r5.xlarge $116.07 $83.22 n1-highmem-4 $108.81 $77.73
r5.24xlarge $2,781.30 $2,002.39 n1-highmem-96 $2,611.43 $1,865.56

What this table demonstrates is that costs can be reduced by shopping around. The savings per instance per month may only amount to a few dollars in some cases; but multiplied by hundreds of instances, the savings can run into thousands of dollars per month—or tens of thousands of dollars per year. While on the subject of shopping around, it can also be worth reviewing what is available in the AWS Marketplace in case another AWS user is selling their excess Reserved Instances at a lower price than AWS.

The key to taking advantage of discount programs effectively

The key to taking advantage of discount programs effectively is to make use of the most appropriate deal wherever it is available. This needn´t necessarily be limited to what one cloud service provider offers, but what is available by comparing AWS Reserved Instances vs. Google Committed Use Discounts (and even Azure Reserved VM Instances) for individual assets.

To achieve the maximum cost savings, you need to have total visibility of your assets, an insight into how your instances are being used, and the right mechanism in place to manage instances across multiple clouds. Once you have total visibility, you first need to determine what the maximum capacity requirements are for each instance and provision them accordingly. For example:

If a four-core instance only requires 12GB of memory, it would be wasteful to deploy an m5.xlarge instance on AWS (monthly cost for a three-year Reserved Instance $62.05) or an n1-standard-4 instance on Google Cloud Platform (monthly cost after a three-year Committee Use Discount is applied $62.42), when the opportunity exists to deploy a customized instance on Google Cloud Platform for the monthly cost of $58.24.

Naturally there are additional factors to take into account when mixing and matching AWS Reserved Instances and Google Committed Use Discounts—such as comparative storage costs and the fact you cannot modify, exchange, or sell Committed Use Discounts—but the saving of ~$4 per instance per month will likely be worth the effort of provisioning instances to match their maximum capacity requirements.

Gaining insight into and managing Instances on different discount programs

Both AWS and Google Cloud Platform offer tools for gaining insight into and managing instances deployed on their own platforms, but not across multiple platforms simultaneously. In order to do this, you need a solution such as CloudHealth´s cloud management platform that enables you to analyze the performance and utilization of all your instances regardless of where they are deployed.

CloudHealth will make recommendations about the most appropriate configuration of your instances so you can take advantage of discount programs effectively. The platform will continue to monitor utilization throughout the life of the Reserved Instance and make further recommendations based on historical usage, reservation types, and expiring commitments, so you can be sure you are always achieving the maximum possible cost reduction without sacrificing performance.