SRAM is fun until you need more than 100MB of it.

There is also a number of other hardware failure scenarios.

God I wish we had denser, regular SRAM. The lack of overhead makes working with old-school async rams a lot of fun - I've only ever talked to DDR via the Xilinx MIG (or the Zynq's Synopsys DDR memory controller IP), and theres just so much more going on than in an old school SRAM.

There are some options, I think MRAM and FRAM do have higher capacities but they're still expensive due to be fairly new...

MRAM is actually very good for rad hardness, but it has a showstopper for bizarre feature of "probabilistic read." Speciality 3T MRAM completely negates that flaw.