> Having a thin provisioning would be great, expecially for the 4TB disks (because i'm sure that 4TB is just a "max recomended sizing" that the "app vendor" wrote in some document for his application sizing)
What's provisioned on storage are...
> Battery backup of a single cache still makes it a SPOF
No, it doesn't.
In your scenario, another, prior and unaddressed, failure is required to make NVRAM (and/or other component(s)) a potential single point of failure.
It doesn't make it a...
The recommended setting is to not touch anything.
What link? The official documentation suggests to not configure any settings (i.e. use the default values)...