Should I use IPv6 – SLAAC or IPv6 – Link Local in AAAA record?

We currently do not support the transfer of IPv6 SLAAC addresses. Link-local IPv6 addresses similarly cannot be transferred and are only used internally as a self-referential address, so you should use the SLAAC address for any Quad-A/AAAA DNS records.

If for whatever reason you need to transfer SLAAC IPv6 addresses, the only way to achieve this would be to migrate your workload onto the Linode that has the specific IPv6 SLAAC you need to use. This could be done either by cloning one Linode's image onto another existing Linode or by copying data from one Linode to another using SCP.

Thanks!

For context, I wanted to upgrade my Ubuntu 18 instance to Ubuntu 22 without having to update DNS records. I was also hoping for the migration to be simple and have minimal downtime.

I ended up doing it by creating a new instance with a clean install of Ubuntu 22, making sure my app works there, then cloning the Ubuntu 22 disk to the Ubuntu 18 instance and updating the configuration to boot from the cloned Ubuntu 22 disk. Finally. delete the Ubuntu 18 disk and delete the Ubuntu 22 instance. I had backed up the Ubuntu 18 instance before all of that.

The actual cloning disk part took about an hour as I tried to understand the disk size requirements. I had originally assumed the cloning would overwrite the existing disk, but on closer reading of the docs discovered it creates a new disk. So I had to resize both the old and the new disk to be small enough that they can exist on the same instance at the same time. (Alternatively, I could have deleted the old disk before cloning. I had backed up the instance, so it would have been safe, I think.)

A feature request might be to have a "swap disks" functionality.