Use C4 Instances

This is documentation for AWS C4 instances. This new generation, low-cost EC2 instance type provides a baseline level of CPU performance with the ability to burst above the baseline.

C4 instances must be launched into an Amazon Virtual Private Cloud (VPC); they are not supported on the EC2-Classic platform. Amazon VPC enables you to launch AWS resources into a virtual private network.

Note: You cannot change the instance type of an existing EC2 instance to a C4 instance type.

General Purpose (C4)

The HVM instance types, available in all AWS regions, are:

  • Large
  • Extra Large
  • 2x Extra Large
  • 4x Extra Large
  • 8x Extra Large

Get started with C4 instances on Engine Yard

This document describes how to use the C4 instances on Engine Yard.


Configure C4 instances

You can configure C4 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 C4 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 C4 instance size.

  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 C4 database instance, you also need to click Apply to update the database.yml file.

Verify C4 instances

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

To verify C4 instances

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

    In general, that is enough of an indication that the C4 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 C4 instances to avoid unnecessary charges.
  4. Stop any unneeded C4 instances to avoid unnecessary charges.


You might have these questions about C4 instances.

How much does it cost?

See the pricing page for details.

Question about size?

The storage type for C4 is EBS only.


This table contains troubleshooting tips related to C4 instances.

Symptom Solution
The C4 instances do not appear in the drop-down list when I try to add an instance. If you have had an Engine Yard account for a while, you might need to create a new Engine Yard account in order to have VPC and use C4 instances. Older Engine Yard accounts did not have VPC.
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 C4 instances.

For more information about... See...
Adding an instance to an environment Add Instances to an Environment
Amazon Virtual Private Cloud (VPC) VPC on Engine Yard
Hardware-assisted virtual machine (HVM) HVM vs. PV
Supported AWS instances on Engine Yard AWS Instance Type Support
Upgrading your environment Upgrade Guide
Adding a database instance to an environment Add a database replica (slave) to an existing environment

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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