The existing AFF8040 is not running 9.6P3 today but it will brought up to this release in advance.
One existing DS224C disk shelf with dual IOM 12's via x4 miniSAS HD to QSFP cables (X66020A-R6) and x2 12Gb SAS HBA's in the AFF8040 (X2069-R6) as the AFF8040's onboard SAS is only 6Gb.
I have sourced x4 miniSAS HD to miniSAS HD cables (X66031A) for connectivity between the existing DS224C and AFF A300. The X66020A-R6 12Gb SAS HBA's are no longer needed as the AFF A300's onboard SAS is 12Gb.
"Using Aggregate Relocation to Upgrade Controller Hardware Running ONTAP 9.5 or Later"
Page 7 - "Deciding whether to use the aggregate relocation guide"
"If you have a system that uses AFF80x0, AFF800, see Using Aggregate Relocation to Upgrade Controller Hardware Running ONTAP 9.0 to 9.4 for detailed information about upgrading ONTAP and relocating aggregates on those systems. https://library.netapp.com/ecm/ecm_get_file/ECMLP2659356"
Is this comment for any AFF80x0 or just AFF80x0's running 9.0 to 9.4 versions?
"This guide provides the steps for the new automated procedure."
"This process is largely automated"
"The manual process was lengthy and complex but in this simplified procedure you can implement a controller update using aggregate relocation, allowing for more efficient nondisruptive upgrades for HA pairs. There are significantly fewer manual steps, especially around validation, collection of information, and post checks. "
After diving into the new guide, I'm feeling less overwhelmed and my confidence is growing. Accepting all institutional knowledge, gotchas, pointers, and hands on experience from all you seasoned head swappers.