What comes to mind when you hear the words big iron? Heavy construction,
extreme laundry, my nickname in high
school. Well, it turns out that big iron
is none of those things and usually refers to mainframe computers, massive
machines that typically live inside of large cabinets. Okay, then Lionus. So,
you're talking about a supercomput, right? Actually, no. Mainframes are
defined a little differently. In our episode on supercomputers, which you can
check out here, we discussed how they
are great at number crunching to complete extremely complex tasks like
weather forecasting, medical research, and crypt analysis. But with mainframes,
the focus is more on throughput and
reliability. So what exactly does that mean? Well,
compared to something like a supercomputer, mainframes have a lot
more inputs and outputs or IO because
they're often deployed in situations where they aren't working on one massive
complex problem, but rather they have to
process tons of smaller, simpler
transactions extremely quickly. In fact,
even though there is a popular misconception that mainframes are relics
of a bygone computing era, to process
the up to millions of card swipes and account transfers that occurred daily,
96 out of the world's top 100 banks and
23 out of the top 25 US retailers
currently run mainframes from IBM, who has been the dominant player in the
industry for a very long time. Building
one though isn't just a matter of installing a whack ton of Xeons in a
box, plugging in lots of Ethernet cables, and calling it a day. Mainframes
use special CPUs, many of which are much
larger physically than even big desktop chips like 2011 socket CPUs from Intel,
as well as additional processors called system assistance processors or SAPs
that do almost nothing but move data
around as quickly as possible, like glorified traffic controllers rather
than general purpose number crunchers. And that's not all. On a modern
mainframe like the topend IBM Z13, each
individual IO card of which there can be
160 has its own processing cores up to two
per channel on the dual channel cards.
Meaning you could have over 600 processor cores just for IO. And that's
not even counting the SAPS. Whoa. Part
of the reason that modern mainframes are designed to support this much IO is to
ensure that they stay reliable. So many of the subsystems inside a mainframe,
like a modern airliner, would have redundancies built in. This means they
can be deployed in situations where zero
downtime is acceptable, such as the aforementioned credit card companies and
retailers, as well as airline ticketing systems. In fact, a common mainframe
operating system, IBM's proprietary ZTPF
was originally developed as transaction processing software for airlines. If you
want to see it in action, pay close attention next time you board a flight,
and you might just get a glimpse of the computer screen they're using to check
you in. An old school interface with green text indicates that it's probably
a terminal connected to a mainframe. just don't look uh too closely at it. So
this high level of redundancy means that it's common for mainframes to be built
in such a way where an administrator can
slide out one of the drawers that houses components and simply start swapping
them out. Whatever that drawer was working on is automatically transferred
over to the rest of the mainframe, making it easy to make necessary
hardware changes without any downtime. which is a good thing, too, because
high-end mainframes can run tons of virtual servers at once, up to 8,000 in
the case of the Z13. Meaning that taking down the mainframe could result in a lot
of transaction errors on Black Friday.
But before you start thinking, gee, I
should get myself a mainframe cuz I want to run Overwatch on like some kind of 50
monitor setup, mainframes and their operating systems aren't just absurdly
expensive. A single mainframe can cost hundreds of thousands, if not millions
of dollars. They also aren't designed to
run games or for high-end floating point
performance, which is important for rendering graphics. But even so, main
frames are still in the background powering lots of things you do every
day, which is pretty cool. That is, unless you've sworn off air travel and
you don't want Mastercard to know about all the weird stuff you buy on Amazon.
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So thanks for watching, guys. Like, dislike, check out our other channels,
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That's the most important part. That's why I said it at the end.