Something like a KVM switch for multiple Raspberry Pis

I fancy setting up a few Raspberry Pis with different configurations.
Their small size would make them ideal for having many of them in a
reasonably small space and I would need them all to be viewable on a
single monitor (by switching).
One monitor, keyboard and mouse would probably do for them all. Anyone
aware of a good-value KVM solution for this? An 8-way would be enough.
Some sort of power distribution would be a bonus. Second hand would be
OK. Cheap components would be a double bonus.
I am not thinking of compute modules as the individual Pis could me
moved later.
Any of you guys already done this?
James
Reply to
James Harris
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Curiously, there seem to be no HDMI + USB KVM switches at anything like sensible prices. There are some HDMI switches cheap, and there are some USB switches cheap, but not integrated.
According to my last search of eBay and the WWW, anyway.
Dave
Reply to
Dave Higton
If they are all networked, the simple solution would be to set up one full machine and use ssh -X to login to the others remotely from that machine. You could also set them up with xdmcp or use vnc (that would be my last choice).
Reply to
ray carter
I would recommend that you try using either RDP or VNC to use one of them to control the rest. Much cheaper, requires no extra hardware.
Dave
Reply to
davehigton14
Not exactly but if they are on your network "sudo apt-get install xrdp" on each Pi makes them standard Windows remote desktop clients . Now you can use a single Windows (or Linux) computer to display the same X Window desktop as that on your Pi. Windows remote desktop makes it easy to automatically log into, and switch between, Pis. It works well and I have never had any need to connect a display, keyboard or mouse directly to a Pi.
I should add that I have not tried audio let alone some other devices that you may be able to connect with a sophisticated KVM switch. To counter that possible disadvantage you can use the power of your Windows box for remote development in Python using Visual Studio or Java using Netbeans.
Reply to
Gordon Levi
I see what you mean. There is a big price difference between an HDMI + USB switch and individual switches. The integrated switches are much too expensive.
Options? Perhaps these:
1. Convert USBs to PS/2s
2. Convert HDMIs to VGAs
3. Have one switch for USB and one for HDMI.
4. Use the network, as others have suggested.
5. Use the olde way and swap cables. :-(
I might have one or two machines in there for which the network would not do as I would need to see them boot up, but it would do in some cases. I could maybe have a hybrid solution mixing different solutions. Sounds a bit complicated and it would not be as convenient as I wanted but may be a practical way forward.
Thanks to everyone for the responses.
James
Reply to
James Harris
I'm a bit late into this discussion but as others have already said I'd be thinking more in terms of network conenction for day to day access. The problem is that both HDMI and USB are a bit too smart to make this kind of thing easy - there is constant two-way communication between the devices so a layer of emulation is needed to give the attahed hosts something to talk to while they are disconnected from the real peripherals. The older PS/2/VGA KVM switches had it a lot easier in this regard.
For initial set-up and emergency access (if it drops off the network) my preference would be for a serial console hooked up to a console server (or a serial access server - they're the same thing). Those aren't cheap new either but if you keep an eye on ebay or similar for a few weeks you'll be able to find a used one going for a song, just don't expect to be able to go out and buy one today for sane money. I picked up a Lantronix 32 port model for £1 seven or eight years ago (plus £10 P&P) and while it's never been more than a third full it's given spectacular service for the money.
Just be sure you are comfortable on a serial line, i.e. a bare command prompt: Unix old hands will feel perfectly at home but if you want everything graphical from the get-go you will find yourself lost.
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Andrew Smallshaw 
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Reply to
Andrew Smallshaw
I wouldn't do it that way.
Ethernet is my preferred solution: I run my RPi headless as a normal host on my LAN and SSH into it from whatever bigger box I'm sitting in front of. If I wanted a GUI on it, it would be equally simple to do that over the LAN.
If you need a lot of RPis, put them all in a common case/rack together
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and you can talk to as many of them as you want simultaneously via SSH, VNC or whatever.
Or you might see if anybody has ported the Beowulf clustering system to the RPi yet - that could be fun to play with.
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martin@   | Martin Gregorie 
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Reply to
Martin Gregorie
It has been done - see, for example,
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raspberry-pi/
Reply to
David James
Thanks. Thats a really nice cluster and the PDF describing how he did it is great too. Bookmarked.
I did have a search for the Beowulf mother lode (or should that be Grendel?) before asking but didn't get far, partly because the saga is much more interesting to the Internet at large and partly because beowulf.org seems to be devoted to a mailing list, its archives and, errm, nothing else. I didn't see anything useful in Wikipedia either.
Do you know if there is a central reference point for Beowulf downloads, update news, etc?
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martin@   | Martin Gregorie 
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Reply to
Martin Gregorie
I'm using a VGA/USB 4-port switch. On that, if I change the display from computer A to B, A gets a disconnection from the USB devices. Actually that is what is needed, otherwise the keyboard and mouse could end up controlling all the computers simultaneously. It does mean I don't want to run the printer through it, otherwise there's a significant chance I will start something printing, then switch computers and disconnect the print stream in mid-flow.
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Alan Adams, from Northamptonshire 
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Reply to
Alan Adams
No idea, sorry.
I only know of that cluster because your posting triggered a vague recollection of having seen something about a Raspberry Pi cluster in the past.
I think I found that one by Googling for "Raspberry Pi cluster" or perhaps "Raspberry Pi cluster beowulf" - there seemed to be other people who had made clusters from Raspberry Pi's too.
Reply to
David James
Who is up for designing a pair of scalable plug-in KVM-over-Ethernet plug in modules for Pi stacks? Pi-side dongle with Ethernet and dual power (USB b + legacy barrel) on one side, with HDMI input, USB b power to Pi, and perhaps an Ethernet-thru port for the Pi, with usb mouse/keyboard control input as a dongle, paired with a User-side dongle accepting legacy PS2 mice/keyboard as well as USB mice/keyboard, dual power and HDMI output? Most setups would have a single User-side dongle and multiple Pi-side modules, but would be able to accommodate several User-side dongles (useful in educational configurations.)
That would satisfy monitoring the start-up.
I am plugging in my pair of Pis to a monitor which accepts up to three HDMI inputs, swapping the keyboard/mouse USB cables when needed, but primary control of each is via Ethernet PuTTY shell and Xming-windows from a laptop, with more than satisfactory results. Reboots are done in the PuTTY command line and I have faith the session can be restarted after reboot. So I rarely need the TV. (save the occasional display of traffic or weather html pages I wrote specifically for my Pi) ?and a clutter of mice. Yet, I still prefer two RPis headless. The R-Pis each allow several students to log-in simultaneously over Ethernet (using donated e-waste laptops) to test scripts, while the instructor laptop runs top to keep an eye on endless loops.
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Reply to
DisneyWizard the Fantasmic!
I'm not completely clear on what you are suggesting. Are you thinking the Ethernet connection could be used to multiplex the user side dongle between multiple Pis? It seems rather a busy device, likely another rPi equivalent in complexity.
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Rick
Reply to
rickman
An out-of-band management device, I think - something that allows remote monitoring and control independent of the operating system.
Reply to
Rob Morley
Put that way, it sounds very like an RPi with USB keyboard+mouse + HDMI monitor plus an Ethernet hub/switch connecting all the RPIs together.
Use the one with keyboard etc to login to the other headless RPis.
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martin@   | Martin Gregorie 
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Reply to
Martin Gregorie
Exactly. Unless there is some advantage to having a device on the pi that actually plugs into the HDMI/USB connectors to emulate the physical devices.
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Rick
Reply to
rickman
...
Sure. Remote desktop or VNC etc can only work on a running OS and, what is more, a running OS which has suitable apps. For bare-metal programming, OS development and to see what's happening in the boot process you need access to the real inputs and outputs.
James
Reply to
James Harris
Then throw out the Raspberries, get a decent Intel/AMD based server, install VMware ESXi and you can do all the "bare metal programming", OS development etc that you like and have access to consoles over the network.
Reply to
Rob
I have tried QEMU as a Raspberry Pi emulator but, IIRC, its emulation was not close enough.
I just looked for VMWare ESXi and found, in common with other VMWare products that it is hard to understand. I am not sure what the difference is between Vsphere and ESXi, for example. I know that Vsphere is a hypervisor but the video describing it spoke of installing ESXi. Two names for the same thing?
ESXi seems to be a type 1 hypervisor. Doesn't that mean that it has to run on a Raspberry Pi in order to emulate a Raspberry Pi?
If I installed ESXi (or some other VMWare product) on an Intel/AMD machine how are you suggesting I get that to emulate a Raspberry Pi accurately?
James
Reply to
James Harris

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