Re:IBM unveils z-series with 5.5 GHz CPU and hardware transa...
by Nerdfest on Wednesday August 29, 2012 @05:58AM
(#4447797)
If you need it done in a hurry, you don't use a mainframe. Their performance is actually quite poor compared to pretty much anything else, as is the cost per transaction. In general, if you need a machine where the hardware never fails, and you can't get the level you need with a cluster, you use a mainframe. Of course, it's still human error that bites you in the ass every time anyway. These days, you really only use a mainframe if that's all you have.
Basically it's a different universe. Everything that might be familiar to someone with a unix or windows background is ... different. More eldritch. More powerful and yet more obtuse.
Oh and JCL. JCL is the devil's work.
One thing they did that I thought was cool was to consolidate a bunch of Linux servers onto their mainframes. They replaced a few racks with z/VM instances. If they needed another server, they could spin it up in literally seconds if the template was already loaded. This was back in 2004, 2005.
You don't buy (actually: rent) a mainframe (actually: CPU cycles and RAM capacity) because it's cost-effective. You do so because the system absolutely must work and you have a mind-numbing number of transactions to process in a hurry.