> Depending on your workload there may be very good economical reasons to consider a mainframe instead of a number of rack-frames. This may be true, but becaus

> Depending on your workload there may be very good economical reasons to consider a mainframe instead of a number of rack-frames. This may be true, but because there's basically no on ramp to running on a mainframe, there's no way anybody is going to try it unless they're already on a mainframe. Or maybe unless they really need something that only a mainframe can provide. But most companies can live with some downtime, and once you can live with some downtime, you have options for migration between sites, and options for migrating loads so you can swap parts on a stopped machine. Splurging on network infrastructure with multi-chasis redundancy is an easier step to take to get to a more reliable system than building against a totally different system architecture.