Large ONTAP upgrade

[EWeber]

I am currently working a project to take 2 clusters from 9.7/9.9.1 up to 9.16.1. Our current hardware is being replaced by 2 C800 clusters that will start at 9.13.1 to be bidriectional with the old equipment (we will be running 9.9.1 prior to the Snapmirror relationship being created) and then upgraded to 9.16.1, so eventually we will have gone from FAS clusters running 9.7 and 9.9.1 to AFF C800's running 9.16.1. Something we've been asked to create amongst all this is a document covering data migration and migration rollback, essentially what the process of migration and rollback is and what would cause us to need to rollback. This has been tricky because we haven't been able to find anything that talks about Snapmirror failing or anything that would cause an upgrade to fail or what to do in that situation. If anyone has any guidance or referencable material that could help it would be greatly appreciated!

[TMACMD]

You never said what the current equipment is. That will ultimately dictate how far you can go with ONTAP

[TMACMD]

Additionally, things to consider

 if you can get both platforms on the same code, you can use SVM mobility (one way transfers of an entire SVM) or if you can get within 2 major version (9.11 -> 9.13 as an example) you can use Snapmirror SVM (aka SVM-dr). When on the same version you can go either way but off you need version separation then you can only go forward and cannot flip back

 notes: if there is any virtualizing (esx, hyper, etc) I migrate those first using host tools ( like storage vMotion). Then anything left use SVM mobility