Cache Transplant

I am brining up my backup server which has lived in various states of disassembly in my basement for a while.

My plan is to transplant my SSD cache from my prod array to the backup server, preserving the appdata and the dockers. This will create redundancy for Dockers that need to run 24x7 should the primary server need to go down for any length of time in the future.

I plan to set up user shares of the same names so that these Dockers feel at home. I am hopeful that the fact that the hostname is different won't affect anything.

Are there any gotchas anyone can think of about doing this operation? Is there anything special I would need to copy over from the PROD array's flash? My disks will be missing downloaded content that the Docker might think is present, but I don't think that should hurt anything. All the appdata is on the cache disk so that should be fine. Not sure I will bring up Plex. It would probably realize that there is no media for it yet, and delete all the content. But Plex is acting as a DVR, and I might like for that to continue to record. Maybe I'll install a fresh Plex Docker and just set up the DVR and nothing else.

I'll then get the backup server running smoothly along with the Dockers. It will be running the relatively ancient 6.0.1 release that has been rock solid for me for so long that I have delayed upgrading and facing some of the 6.3 challenges. Episodes my Dockers download can be copied over and manually applied to the primary server later.

Then I will turn my attention to the prod array, and upgrade to the latest version (6.3.4 I suppose) and run it through its paces. I'm planning on a virgin install. I have a new 500G SSD for that server, and will use it to create a new Docker file. Once done I plan on installing the Dockers and hopefully having them scan the files to register my content, rather than try to migrate any old appdata. I plan to transition to some new versions / branches of my Dockers to take advantage of new features. Once I get this setup, I will shut down the Dockers on the backup server, and migrate any data to the prod array.

I would like to be able to refer to the backup array from the prod array and vice versa. What is the best way to set that up? Can I do some type of bidirectional mounting? This is new territory for me with Linux.

TIA from some input on my plan!