Hibernate | Notion

Hibernate is like putting your laptop into sleep mode instead of shutting it down.

When you normally stop an EC2 instance, everything in RAM is wiped. Next boot starts fresh — OS loads again, applications initialize again, which can be slow.

When you hibernate an EC2 instance, the entire contents of RAM are saved to the root EBS volume. When you start the instance again, that RAM state is reloaded and the instance resumes exactly where it left off.

Normal Stop vs Hibernate:

	Normal Stop	Hibernate
RAM data	Lost	Saved to EBS
Next boot	Fresh start (slow)	Resume from saved state (fast)
OS restart	Yes	No

How it Works

Instance running → Hibernate triggered
    |
RAM contents written to root EBS volume (encrypted)
    |
Instance stops
    |
Start instance again
    |
RAM contents loaded back from EBS
    |
Instance resumes exactly where it left off

The OS is never restarted. Boot time is very fast because the system just reloads memory rather than initializing everything from scratch.

Requirements

Root volume must be EBS (not instance store)
Root EBS volume must be encrypted — RAM contents may contain sensitive data
RAM size must be less than 150 GB
Instance families supported: C3, C4, C5, I3, M3, M4, R3, R4, T2, T3, and more
Bare metal instances are not supported
Supported AMIs: Amazon Linux 2, Linux AMI, Ubuntu, RHEL, CentOS, Windows
Purchasing options: On-Demand, Reserved, and Spot instances
Maximum hibernate duration: 60 days — an instance cannot stay hibernated for more than 60 days