Can't launch ec2 spot instance with hibernation for instance type c5.18xlar

Question

I'm trying to launch a spot instance with the following settings:  
AMI: ami-06f2f779464715dc5  
Instance type: c5.18xlarge (72 vCPUs and 144 GiB of memory)  
Storage: root EBS with 100 GiB and added an encryption key  
Volume type: General Purpose SSD (gp2)  
  
As far as I can tell the above settings meet all the requirements for hibernation interruption behavior as described in https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Hibernate.html#hibernating-prerequisites but still I see the message: "Selected instance type does not currently support 'hibernate' interruption behavior."  
  
Changing the instance type to be c5.9xlarge (36 vCPUs and 72 GiB of memory) with the same settings does allow me to choose hibernate as interruption behavior.  
Any idea what is missing?  
  
Thanks.

Answer

Hi,  
  
The prerequisites for hibernating a Spot Instance are slightly different to the prerequisites for hibernating an On-Demand Instance.  
  
For the instance RAM size:  
- Spot Instances – must be less than 100 GB  
- On-Demand Instances – must be less than 150 GB  
  
There are different pages in the EC2 User Guide that describe the hibernation prerequisites for Spot Instances and On-Demand Instances.  
- Hibernation prerequisites for Spot Instances: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/spot-interruptions.html#hibernate-spot-instances  
- Hibernation prerequisites for On-Demand Instances: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Hibernate.html#hibernating-prerequisites  
  
Kind regards,  
Marilyn

Answer

I missed the conversion between GiB to GB.  
The memory limit in the description is listed in GB but the instance details are in GiB.

Can't launch ec2 spot instance with hibernation for instance type c5.18xlar

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