Resizing your EBS-backed instances has been simplified considerably by Amazon in the last couple of years. Here’s the process and what to watch out for.
Compatibility Requirements
Before attempting to resize, verify three things:
- Platform: 32-bit and 64-bit instances cannot be converted to each other
- Virtualization type: HVM instances cannot be resized to Paravirtual (PV) formats, and vice versa
- Network configuration: Certain instance types require VPC deployment and are incompatible with EC2-Classic
Steps
- Open the EC2 console
- Stop the target instance
- Select the instance and navigate to Actions → Instance Settings → Change Instance Type
- Select your desired instance type - the dropdown shows only compatible options
- Start the stopped instance
That last step sounds obvious, but I forgot it once and caused 3 minutes of unexpected downtime. Don’t be me.
Key Takeaway
The process is straightforward. The dropdown filters out incompatible instance types automatically, so you won’t accidentally select something that won’t work. Just remember to start the instance after making the change.