A massive 4U IBM eServer, designed to bring mainframe-style power to the Intel world. Its front facade is pocked black: holes let air flow in. There are only two drive bays, because no one uses local hard drives in a machine this big. Its power supplies--and there are only two--prefer 220 volt power, so that the machine can keep running if one supply fails.
This is the machine from IBM commercials that sits like a monolith on the table, while the narrator says it can "almost heal itself." "Lightpath diagnostics," or orange lights visible if you open up the server, are supposed to let you know where any hardware problem is located. A blue light flashes on the outside if the machine is not in a "known state," like when it's rebooting.
Slide this machine out from the rack, and you'll see two silver doors latched together with black plastic. It opens like a cabinet. You'll notice all the orange: on the fans, the PCI card tabs, the RAM. Orange means "hot-swappable". Yes, if your OS supports it, you can theoretically hot-swap RAM.
The left half of the server holds around eight fans and has slots for at least eight PCI cards spread over four buses. Depending on your configuration, the right half may have a baffle on top. Under the baffle is an "expansion module", which is a black box with a handle. You can take the module out when the server's off. The expansion module has room for 4 CPUs and 16 sticks of RAM.
You can have more than one expansion module. You just take the baffle out, and drop in your second module. Two expansion modules means up to 8 CPUs and 32 sticks of RAM. What's more, you can buy another machine and connect its expansion modules to the first machine: 16 CPUs and 64 sticks of RAM. IBM supports up to four machines connected together: 32 CPUs and 128 sticks of RAM. Red Hat has a special kernel, just for this machine: the "summit kernel."
These processors support hyperthreading. Each physical processor appears as two logical processors to the operating system: your OS can see 16 logical CPUs from two expansion modules.
When you first install a 445, special handles are attached to the sides of the server so you can carry the chassis easily. The handles also let the machine rest on its rails while you screw the chassis in to the rack mounting.
When adding hardware, I learned that you should never unmount the 445 from the rack. In my excitement to put in a second expansion module, I took the server out of the rack. I put the parts together and carefully added the module to the server. Then I realized that the special install handles were gone, there's a note on the server that says "76 lbs," and I was alone. Either I could call for help--interrupting someone's weekend--or improvise. So, I stacked cardboard boxes and installation manuals to provide a base, then dragged the server on them so that I could screw the server into the bottom of the rack. I used my knees, too, to push the server up so that each of the eight tiny damnable golden screws would fit, snug.