Comment by derefr | Hacker News Reader

Comment by derefr | Hacker News Reader

I’ve seen those “support element” laptops hanging off of racks before, but I always assumed that in this case (IBM mainframe, IBM support element, vertical integration) they were not laptops as such, but rather thin clients in the most literal sense: just IO interfaces with a ribbon cable feeding back to the mainframe, where the framebuffer of the mainframe’s dom0/maintenance VM was pushed over VGA and keyboard+mouse+peripherals were returned over USB. Essentially as if the support element were a Thunderbolt Display with USB HID devices plugged into it. Like a modern VT100!

I’m honestly surprised to learn that I’m wrong, as having the laptop be a real laptop would introduce all sorts of headaches compared to having the laptop be a dumb terminal—it’d have active components like disks and fans that could to burn out (and not be hot-swappable like the server’s own components are); and more importantly, it’d have to talk to the server using some form of network interface (unless it’s just a glorified glass terminal for a USB-serial adapter.) In which case, bad behaviour on the server—exactly the case where you need a local admin console—could block or steal resources from your connection attempt. You may as well just be SSHing into the dom0 from across the room over the SBC VLAN at that point.

The support laptop on an IBM mainframe is analogous to the setup on a Cray machine. The System Management Workstation or 'SMW' (previously a Supermicro tower workstation with a bunch of ethernet), now a Dell Poweredge rackmount is its own system which controls the rest of the machine--booting, shutdown, and all of the other myriad maintenance tasks on a cluster like that. It's also responsible for building boot images and interrogating the low level controllers on each rack and on system blades themselves.

During bringup of a machine like that, the SMW host is installed first from scratch with a Linux distribution, hardware inventory is enumerated, boot images are built for individual node roles in the system and then the system performs its boot procedure.

The new iSeries we bought (Power S914) uses a Windows computer as its terminal. I would prefer a dedicated terminal with all the keys, but that how it goes now. One thing about it, the tech that is doing the installation is remoted into that PC doing the steps to copy our old machine to the new one.

On a side note, the new machine has LTO-7 and our old machine (9406-800) predates LTO, so it makes the upgrade a bit longer.

Support element has to be more or less full-blown computer as the mainframe itself does not have any real firmware to boot^H^H^H^HIPL itself. Before support elements the IPL process involved initalizing various things by toggling switches on the console.

Also why the mainframe would even have a framebuffer?

Providing a console interface (ie. 3270 terminal emulator) to whatever OS runs on the mainframe is only small part of what SE does.

> real firmware to boot^H^H^H^HIPL itself.

Have you considered using ^W?

No ^W in Emacs nor ISPF ;)

Just a word of caution for anyone reading this. I highly discourage anyone from actually learning ^w. I learned it, then had to forcefully un-learn it when I kept accidentally closing tabs on my browser, other people's browsers, my file manager, etc. etc. ad nauseam. Don't make the same mistake I did, just press backspace a lot. I know life is short but the sudden rage of having unexpectedly closed a tab is just not worth the added efficiency. I am passionate about this subject; however, I mean no disrespect for those who have (somehow) managed to use ^w productively.

> Also why the mainframe would even have a framebuffer?

The mainframe itself wouldn't, but it might be running a VM that has one (and also has reserved capacity on the system, preventing other tasks from fighting it for priority.) I was picturing the support element as simply a physical extension of that VM, sort of like x86 VMs can use IO-SRV to lay claim to graphics cards and such. It'd be like the BMC on an x86 server motherboards, but virtual.

What you say about the support element also being used to IPL the system makes sense, but I'm surprised that responsibility is pushed into such a fragile component as a laptop. Why not just make the "IPL booter" a single-responsibility SoC card-edge daughterboard (I'm picturing a game-cartridge-looking thing), and leave the support element for, well, support?

All of which would require the customer to make one of those lovely support calls and create opportunity for upselling!

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