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Use C3 Instances

This is documentation for AWS C3 instances. This new generation of EC2 instances provides the power and speed that you need for your compute-intensive applications. In comparison to the C1 instances, the C3s provide faster processors, and approximately double the memory per vCPU and SSD storage.

Compute Optimized (C3)

The 64-bit instance types, available in all AWS regions, and optionally as dedicated instances, are:

  • Large
  • Extra Large*
  • 2x Extra Large* Hidden behind feature flag
  • 4x Extra Large* Hidden behind feature flag
  • 8x Extra Large* Hidden behind feature flag

* Extra large, double extra large, and quadruple extra large instances are also available as EBS optimized instances.

Get started with C3 instances on Engine Yard

This document describes how to use C3 instances with Engine Yard.


  • This article assumes you already have an Engine Yard account. If not, see Sign up for an Engine Yard Account.
  • You must add a new instance to use this feature. You cannot modify an existing instance / volume.
  • You must use 64-bit instances (32-bit instances are not supported).
  • If you are using the Engine Yard Gentoo 2009 stack, you must click Update for the December 13, 2013 stable-v2 stack upgrade to gain C3 instances support.
  • If you are using the Engine Yard Gentoo 12.11 stack, you must click Update for the December 13, 2013 stable-v4 stack upgrade to gain C3 instances support.

Configure C3 instances

You can configure C3 instances when you add new instances to a new or existing environment.

Note: We recommend testing in a staging environment before applying changes in a production environment.

To add a new C3 instance

  1. Ensure that you meet all the prerequisites above.

  2. Add an instance in the usual way.

    See the database docs for more information about adding a database instance to an environment.

  3. Select the appropriate General Purpose C3 instance size in the list.

    C3ComputeOptimized list.png


    • Some instance sizes may not be available by default. Please contact Engine Yard Support if you do not see the necessary instance sizes.
    • Dedicated instances might not appear if you have had an Engine Yard account for awhile. See the notes in More information.
  4. Click Add to Cluster (or Boot This Configuration, if you are re-booting an existing environment).

    See the related documentation for more information on adding instances to your environment.

    Note: If you are adding a C3 database instance, you also need to click Apply to update the database.yml file.

Verify C3 instances

Note: When you are testing in staging, consider the differences between your test and production loads.

To verify C3 instances

  1. Ensure that instance provisioning worked and the instance is running.

    In general, that is enough of an indication that the C3 instance is working fine.

  2. Review the Troubleshooting tips below for more information.
  3. If this is a staging environment and you are finished with testing, be sure and stop any C3 instances to avoid unnecessary charges.
  4. Stop any unneeded C3 instances to avoid unnecessary charges.


You might have these questions about C3 instances.

Why is the cost of C3 instances higher?

Your C3 instances provide about double compute power and so cost a bit more. See the pricing page for details.

How can I use the SSDs on these instances?

You can leverage the SSDs as needed via custom Chef; be aware that there is no ability to create snapshots of SSDs.


This table contains troubleshooting tips related to C3 instances.

The C3 instance will not provision in any AZ in the region I selected. Amazon is working to increase capacity of C3 instances. In some cases, limited capacity will result in provisioning errors. See the known issue for more information.
When I clicked HTTP on the app server, I received a 500 Internal Server Error. If this is the first time provisioning, wait a few minutes and try again.

More information

This table provides other resources related to C3 instances.

For more information about...See...
Adding an instance to an environment Add Instances to an Environment
Adding a database instance to an environment Add a database replica (slave) to an existing environment
EBS optimized instances EBS optimized instances
Dedicated instances Dedicated instances

If you have feedback or questions about this page, add a comment below. If you need help, submit a ticket with Engine Yard Support.

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  • Avatar
    Luke Ludwig

    Great! Excited to use these. What is the pricing on these… can't seem to find it anywhere.

  • Avatar
    Tasha Drew

    Hi Luke, 

    We are finalizing pricing and adding all that info to our website and billing system right now, but wanted to make the instances available ASAP as we do that. 

    I'll email you with the current projected prices (waiting on final CFO approval).


  • Avatar
    Tasha Drew

    Ok, pricing has been finalized, we'll add these to the pricing calculator shortly: 

    c3.large $0.29/hr

    c3.xlarge $0.56/hr

    c3.2xlarge $0.95/hr

    c3.4xlarge $1.75/hr

    c3.8xlarge $3.09/hr

  • Avatar
    Fernando Calatayud

    Amazon: c1.medium -> $0.165/h, c3.large -> $0.171/h, +$0.06    -    EY: c1.medium -> $0.22/h, c3.large -> $0.29/h, +0.70... I don't like that pricing, your margin goes from 33% to 70% for the same services!!

  • Avatar
    Tasha Drew

    Hi Fernando, 

    Our margin/revenue is not exactly proportional to re-selling infrastructure; as a platform, we have many other facets and value-adds that do not directly correlate to instance pricing. Additionally, we include standard support from our world wide support team in our base pricing, along with many other platform features.

    We have made the C1's very affordable over time as we saw they were a popular size for customers. We are planning on doing the same with the C3 family over time as we gauge interest in this instance type (You will notice that C3's are still in early access on our platform). This requires forecasting and investment on our part as we work with this infrastructure partner, AWS. 

    As always, if you'd like to contact your sales rep (sales@engineyard.com), we have several ways that you can take advantage of lower pricing. 

    Cheers, Tasha 

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