I was referring to setups where there is just an HDD attached to the pi, or anything else. it will be game over once node requires over 200-ish iops HDD can provide. Adding SSD cache would help address this, but it’s not longer “hdd on pi” setup.
I thought products like ZimaBlade at $64 would be ideal candidates. Two SATA ports to start with — one for HDD, one for SSD cache, and 4-lanes PCIE 2.0 port, to plug in the HBA instead and have a proper storage solution.
That’s on expensive overkill though.