FortiAnalyzer AWS AMI Expiration

Hello Community,

We are about to deploy Fortianalyzer in AWS (BYOL). One of the concerns we have is regarding the expiration of the AWS Fortianalyzer AMI image that we will be using. 

In case the image becomes unavailable in AWS in few years and knowing that we cannot detach the disk of the VM and reattach it to another VM, what would be the best strategy to migrate to a new VM with newer AMI without losing our existing logs?

Any advise would be much appreciated.

Thanks