In this post and subsequent ones, I will discuss the main hardware concepts of mainframe environments. I will not go into the tiniest detail, but I must be a bit technical. To make things easier to understand, I will compare the mainframe technology with mainstream x86 and Unix technology. You will see there is often a difference in terminology.
The mainframe has a long history. Some hardware terminology is different from what we know. To get some understanding of this hardware we need to talk a little bit about mainframe jargon.
This post appears as part of a number of articles in the category “Don’t Be Afraid Of The Mainframe.
A mainframe is a large refrigerator-size box with computing capacity. The box houses the computing units, the CPUs. These are not x86 CPU’s like in your PC. But a mainframe uses CPU’s build according to the processor architecture called IBM z/Architecture.
In your PC, the CPU, the memory and other chips are soldered on a motherboard. Like in your PC, you find a sort of motherboard in the big mainframe box. The mainframe motherboard is called a drawer. The drawer is a bit bigger than your PC motherboard because it carries more components.
On the drawer the CPU and memory chips for the mainframe are soldered, and some more components. A drawer can have a number of CPU chips. In the z14 model the number of CPU chips in a drawer can be 6.
Each CPU chip on the drawer has a number of processor cores, the actual CPUs. The number of processor cores varies per mainframe model. In the z14 mainframe model there are 10 cores on a chip.
Finally you can have multiple drawers in a mainframe box. In the z14 there can be 4 drawers.
Now let’s count. You can have a maximum of 4 drawers, each with a maximum of 6 CPU chips, each chip with 10 cores. Thus, you can have 240 processor cores in a mainframe box – the z14 model to be precise. The mainframe uses a number of these 240 cores for internal processing. For you as a mainframe user up to 170 processor cores in a single mainframe box.
You also need memory. Every drawer can have a maximum of 8 TB of memory in the z14. So in total you can have 32TB of memory in your z14 mainframe.
Enfin, a lot of computing power.
Besides the main computing elements, CPU and memory, the mainframe server contains almost everything else needed. Power supplies, network cards, cooling devices, I/O cards, and more .
To make sure the mainframe can continue running when one of these components fails, you find at least two items of these components in a mainframe.
In the picture of Figure 3 you can see the following components:
- Processor drawers – as we saw, the motherboard of the mainframe. There can be multiple processor drawers in a machine, depending on the number of CPUs you have ordered.
- PCIe Input Output drawers in which cards are configured for networking equipment, IO interfaces (disk, tape, server-to-server connections) and additional facilities such as encryption and compression. PCIe is a standard for interfaces in a computer.
- Cooling components to regulate the temperature. A mainframe box can be water-cooled or air-cooled, by the way.
- Power supplies to provide power for the components in the machine.
All in all, it looks very much like a normal computer, but a little bigger.
In the picture you also see two laptops. As we will see later, the big box needs to be configured. The two laptops are so-called support elements. With these support elements you can configure the hardware, and also monitor the state of the hardware.
More technical information on mainframe hardware can be found here: