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Migration of EC2 from old to new generation (Nitro System)











Problem: During the migration of EC2 from older generation to newer generation that runs Nitro System, the system fails to boot

Root Cause: We have 2 EBS attached and if the booting process involved the use of the second EBS, the booting will fail. In our case, we moved /var to another EBS. The reason is the in /etc/fstab, it refers to a /dev which no longer exists.

This is due to new referencing convention used by Nitro System. Instead of /dev/xvdb1 etc, they become /dev/nvmen1p1 and so on.

Solution:

1. Before switching instance to new generation, change the /etc/fstab

e.g. from /dev/xvdb1 to /dev/nvme1n1p1

2. Stop the instance via AWS Console

3. Switch to the new instance, start instance

Depending on how the dev is initially formatted, the change could be:

e.g. from /dev/xvdb1 to /dev/nvme1n1 (i.e. without "p1")

With the server upgrade to newer generation under AMD architecture, there is a cost saving of >15% and better network I/O. This upgrade exercise makes economic sense.

More about AWS Nitro System: https://aws.amazon.com/ec2/nitro/



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