But you should plan on partitioning to multiple db servers up front and save pain of conversion later on. A dual socket motherboard with 16 to 32 SAS drives and a fast RAID controller is WAY cheaper than a similar machine with 4 to 8 sockets is gonna be. And if you gotta go there anyway, might as well spend your money on other stuff.
I agree. If you can partition that sensor data across multiple DBs and have your application do the knitting you might be better off. If I may be so bold, you might want to look at splaying the systems out across your backends. I'm just trying to think of a dimension that you won't want to aggregate across frequently.
On the other hand, one of these 16 to 32 SAS drive systems with a raid card will likely get you a long way.