[rodgerd]

> Is that a single-system image

No. Which workloads do you have that need more than 40 cores per image, are happy with a maximum of a hundred on, and won't run on clusters? (I hope it's not one that's going to be crippled by zVM's slow scan of large memory areas suspending guest execution).

> I/O offloaded

If you've actually worked with zLinux (I have) you'll know there's little effective offload, and that zVM overhead increases as the virtual IO ramps up.

> and five 9's

Is zVM offering sysplex? No. So you're relying on your single LPAR to be five nines? Never upgrading zVM? Never updating PR/SM?

Is the datacentre five 9s? The power? The network? Really?