Density is also bad. You spend 4 full racks and get 208 cores. Sure, they might be the fastest cores around, but that gets you only so far when even off-the-shelf Dell server has 2x128-192 cores in 1U server. Similarly 64 TB of RAM is a lot, but that same Dell can have 3 TB of RAM. If I'm reading the specs correctly (they are bit confusing), z17 has only 25G networking (48 ports); the Dell I'm checking can have 8x200G network ports and can also do 400G networking. So the single 1U commodity server has more network bandwidth than the entire 4 rack z system.
Sure, there will be lot of overhead in having tens-hundreds of servers vs single system, but for lots of workloads it is manageable and certainly worth the tradeoff.
Sure, there will be lot of overhead in having tens-hundreds of servers vs single system, but for lots of workloads it is manageable and certainly worth the tradeoff.