The new FAS8040 single and dual controller configurations come in one chassis only.
I believe that this is not full HA best practices, and may not supply best uptime in case of chassis hardware failure.
(for example, we had, last week, a FAN failure that was caused due to sensor problem inside the chassis. The replacement required full downtime. Since we have 3240HA system with 2 chassis, there was no downtime to our clients).
The only solution I can think of is metro cluster. But this will require x2 disks (and controllers).
"Passive" means as close to a simple piece of metal, as possible, hence extremely unlikely to fail for whatever reason (rust? )
Dual chassis setup IMHO still has an advantage though, as cabinet-level resiliency can be fairly simply achieved.
However, 100% *guaranteed* uptime is a myth - an unexpected can always happen. We had cases of controller panics during an NDU ONTAP upgrade, which meant downtime on an otherwise perfectly healthy hardware.
I'd also be interested to find out NetApp's reasons for single chassis architecture. We are currently assessing an option to perform an in-place controller replacement from FAS 32xx to FAS80xx, however we have each FAS32xx chassis in separate racks and we will need to compromise to move to a single chassis (either a huge outage to shuffle disk shelves, or put the controller in a 3rd rack and leave a few 3RU gaps in the existing racks).
Is there any news as to whether NetApp is considering releasing dual-chassis models in the near future?