What is a Mainframe Computer?

I bet lots of people will look at you funny if you ask them, "What is a mainframe computer?" or "Do you know what a mainframe is".

Let me tell you a secret. Mainframe computers is not that different from any other computer out there. It's a computer, so the basic components stays the same. They also have CPU, memory, hard disks and network.

The term, mainframe, comes form the good old days when these systems were huge and all their components were housed in large metal cases. They are also known as "Big Iron" or "Heavy Metal". Mainframes used to be very large and it took lots of people to operate and maintain them.

They also ran their own type of operating system called MVS (Multiple Virtual Storage). The MVS operating system ran on the IBM System/370 and IBM system/390. It was released in 1974 and has since gone through a lot of versions.

The last version I worked on was the MVS/ESA (Multiple Virtual Storage/Enterprise Systems Architecture) and this was on a IBM System/370 and yes, it was a long, long time ago. I can hardly remember the commands anymore.

These system were huge and they were heavily used by big companies such as financial institutions, government institutions and educational institutions. They could easily take up the space of small house, sometimes even larger.

To give you an idea of the size, below is a tape drive unit that could store a maximum of 250MB. Look at the size of the thing!

The 6250 tape storage drive used big reel-to-reel tape devices to store the data on. Below is a picture of what these tapes looked like. There were usually hundreds of the tapes used to store data and for system backups.

Mainframes used to be very complicated to work on and you needed a whole team of people to make this thing work. Today's mainframes are much smaller than it's predecessors and the operating systems have also changed to a more UNIX like OS.

The IBM z10 is IBM's mainframe and it runs a operating system called z/OS. You can even run IBM's Linux on these mainframes.

So why would a company use a mainframe computer if it's that big? Computers were not that powerful 20 years ago as it is now. PC's were running single CPU's and UNIX servers were still getting if the ground. Mainframes were the answer cause it could manage a large workload.

They could also take more than one CPU and they could also be partitioned to multiple operating system on a single chassis. Mainframes were virtualized before any one else did it, and they are still using that technology today.

In a sense you could say that mainframes started the whole virtualization technology drive.

Like I said earlier, mainframes are not that different from other big servers that companies such as Oracle and HP produce. Oracle Sun's M9000-64 can also be partitioned into dynamic system domains and these domains can then be further divided into smaller partitions called zones.

This gives you the same flexibility as mainframes, and the physical size between the M9000-64 and a IBM System s10 is not that much different. Oracle, at some stage, sold their M9000 as a mainframe class computer.

Are mainframes still used today? Yep, companies that still produce mainframes are IBM and Fujitsu. I don't know how they are selling these days, but more and more companies are moving to greener, smaller and more powerful servers.

They may not be that popular any more, but they are still used today.

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