Ask Slashdot: Advanced KVM Switch?

jez9999 writes: I have a rather advanced use-case for my home work area that I need a KVM-type device for, and I was wondering whether such a thing even existed. I want a 3-PC setup; 2 desktops (PC1 and PC2) and 1 laptop going through a dock (DOCK1). I want to connect 2 monitors (SCREEN1 and SCREEN2), 1 mouse, and 1 keyboard (INPUTS). So far it's relatively straightforward, as I could just switch everything between the 3 devices.

But here's the kicker; I'd like at least 4 modes of operation: one mode to output PC1 video to both screens (dual-screen) and redirect INPUTS to it, one mode to output PC2 video to both screens (dual-screen) and redirect INPUTS to it, one mode to output PC1 video to SCREEN1, extend DOCK1 video to SCREEN2, and redirect INPUTS to DOCK1, and one mode to output PC1 video to SCREEN1, extend DOCK1 video to SCREEN2, and redirect INPUTS to PC1.

Basically with the latter two modes I'd like to be able to switch between inputting to PC1 & DOCK1, whilst continuing to be able to monitor each by outputting each one's video to one of the 2 monitors. However, I also want to be able to go dual-screen with and control PC1 & PC2.

In terms of ports I'd like to use HDMI (or possibly DVI-D) and USB for peripherals; not VGA or PS/2.

Is there any KVM switch out there able to do this kind of thing? I guess I'm probably looking for some kind of programmable KVM which allows me to specify, for each 'mode of operation', which inputs are routed to which outputs. Failing that, is there some other way I can get the setup I want (or something close)?

Comments

Matirx KVM Switch

[BenFranske]

What you want is called a matrix KVM switch. They exist, but they're quite expensive, do some Googling on matrix KVM switch and you'll see the options.

Re:Matirx KVM Switch

[BenFranske]

See the ATEN CM0264 for a specific example of what I think you're looking for.

Re:Matirx KVM Switch

[Qzukk]

You can also try searching for a "Multi-Console" KVM switch too. No, they're not cheap either.

Re:Matirx KVM Switch

[cdrudge]

A separate 3x2 or 4x2 HDMI matrix switch and USB switch would be significantly cheaper than a all-in-one solution. It would be a few extra button presses, but for the money saved it wouldn't be that bad.

Re: Matirx KVM Switch

[amxcoder]

This. Run video through a matrix HDMI switch, (4x2 or 4x4) will allow you to route the video any way you want, any input to any output. Then use a normal USB KVM for keyboard and mouse control.

Re:Matirx KVM Switch

[DarkKaplah]

BenFranske is correct. You're looking for a matrix switch for the video. They are sized by the number of video inputs and outputs. You're probably looking for a 6x2 ( inputs( pc1 screen 1, pc1 screen2, pc2 screen1, pc2 screen1, laptop screen1, laptop screen2) x outputs (screen 1, screen2). Remember these devices will not use a keyboard shortcut to direct sources to outputs. You'll either need to use the remote or rig something up with an arduino as most of these devices accept RS-232 commands that are fairly simple.
Something like this would work http://amzn.to/1L2pWmU

As for inputs such as keyboard and mouse that would be something different. I used a USB switch and a hub to create this solution, but now this type of gear exists.
http://amzn.to/1FB3dyd

I believe this would solve your issue. Your other choice would be to get two 4 port HDMI KVMs each hooked up to a monitor. You only need to hook a keyboard and mouse up to one (say screen 1's kvm). The issue here is you'll have to use the remote or buttons to trigger Screen2's KVM as you won't be able to use a keyboard shortcut where as you can on Screen1.

Hope this helps!

Re:Matirx KVM Switch

[KVM Guru]

That is super expensive, doing a quick search I found that ConnectPRO UDD-14A+ can do what he wants for about $500

Re: Matirx KVM Switch

[Anubis IV]

Completely agree with you, since that'll save a load of money and complexity headache. If he is, however, absolutely dead-set on a KVM and wants to avoid a matrix KVM, he should recognize that he really has three modes (i.e. one per computer), with PC1 having two modes (i.e. toggling between what's displayed on the second display). Doing so greatly simplifies things, since it lets you use a normal dual-screen KVM switch to control your inputs, then use a simple HDMI switch to toggle what's shown on your second display when controlling PC1.

A complete example setup might be:

PC1 SCREEN1 goes into an HDMI splitter, which goes to KVM Port 1 SCREEN1 and KVM Port 3 SCREEN1. I.e. For controlling both PC1 and DOCK1, you'll see PC1 SCREEN1 on your first display.

PC1 SCREEN2 goes into an HDMI switch, which then goes to KVM Port 1 SCREEN2.

PC2 gets hooked up like normal.

DOCK1 SCREEN1 goes into an HDMI splitter, which goes to KVM Port 3 SCREEN2, as well as the HDMI switch mentioned earlier. I.e. DOCK1's video will always be visible when controlling DOCK1, and will optionally be visible when controlling PC1.

Everything else hooks up like normal. At that point, he'd use the KVM switch to control which computer he's using, then would use the HDMI switch to toggle whether he sees PC1 or PC1/DOCK1 when controlling PC1.

That said, HDMI splitters are notoriously flaky, particularly if you go for the passive variety.

Re:Matirx KVM Switch

[Lumpy]

Wont work unless the HDMI matrix has EDID management so the computers do not see the displays appearing and disappearing.

You need a good quality one, not the junk from monoprice. About $1100 for a good 4X4 with full edid management.

Re:Matirx KVM Switch

[viperidaenz]

The ATEN CM0264 is cheaper than that. It's $500NZ, including sales tax. which is roughly $320US

Re:Matirx KVM Switch

[rwa2]

Resolution matters. Distance matters. Peripherals matter.
Start with the ThinkLogical VX40. You will need some transmitters and receivers and you may want a server to run the switching software. They have some optional keypads. They can also use either MMF or SMF, if you need to extend more than a few hundred meters.

This. I've deployed half-million dollars' worth of Thinklogical KVMASS networks for $LARGEDEFENSECOMPANY$ before and they were great to work with. If money is no barrier, these fiber modems and crossbar fiber switches will let you do just about anything. Full lossless digital transmission, and measurable but barely noticeable latency of maybe 100ms. One fiber carries the video (or two, if you need dual-link DVI bandwidths), and another carries the bidirectional KMASS (keyboard, mouse, audio, serial, uSb). The video can be routed independently of the KMASS, and the last rev of the WebUI that I saw about a decade ago was pretty good with complex presets and stuff. The fiber routers ran some flavor of Scientific Linux, so I could get in there and install extra python scripts that would allow it to take other control protocols.

There were some minor problems with some USB drivers... by default a keyboard / mouse would be patched through via a virtual compatibility layer that might cause issues if you were using a fancy keyboard, but there are options that let you use the KM in "dumb" USB mode (which means a bit more latency when switching KMASS as the OS has to re-detect your HID each time, and maybe trouble booting if your BIOS whines about not detecting a keyboard). And only one console could have control of a workstation at a time. Maybe the biggest annoyance for "traditional" KVM switch users is that they didn't have any keyboard shortcuts at the time, so you needed another control station to request switches. But it was certainly the best approach for giving us "any console, anywhere" from a visualization farm in one or more server rooms to any operator console anywhere in our facility.

Re:Matirx KVM Switch

[jez9999]

That switch doesn't seem to have a dual-screen option; just single screen for 4 devices.

Re: Matirx KVM Switch

[jez9999]

Sorry to seem lazy, but could you provide a couple of examples of KVM switches that will allow me to route the video any way I want? All the ones I can see always route the video from one device to the console at one time, or don't provide the option for dual-screen functionality.

Re:Matirx KVM Switch

[jez9999]

What you want is called a matrix KVM switch. They exist, but they're quite expensive, do some Googling on matrix KVM switch and you'll see the options.

Well there's certainly a bunch of them out there, but I still can't see one that does exactly what I want, even if I just stick to video and ignore the USB aspect of it. Could you provide an example of one that takes in a bunch of dual-monitor HDMI inputs, and allows either dual monitor output to 2 monitors, or single monitor output for any one of the inputs to each screen?

Re:Matirx KVM Switch

[KVM Guru]

Where did you see that cause looking on Amazon I found the Aten one for $2000 $1400 and one $650 all USD?

Re: Matirx KVM Switch

[amxcoder]

My suggestion was to NOT use the KVM for the video portion, just the USB Keyboard/Mouse portion of control. My suggestion would be to use a small HDMI video matrix router for routing the video where you want it (seperately from the KVM control).

Others have suggested using a martrix KVM, but I haven't ever seen/used one of those beasts before and didn't know they existed. And apparently are expensive.

Re:Matirx KVM Switch

[viperidaenz]

http://www.pbtech.co.nz/index....

Re: Matirx KVM Switch

[jez9999]

OK so you're drawing a distinction between KVM and "HDMI matrix switch". Could you suggest one or two good HDMI matrix switches then?

Re:Matirx KVM Switch

[jez9999]

Why on earth do all these matrix devices use IR remote controls that are liable to break easily? Is it so hard for them to just put buttons on the switch itself? Literally all of them seem to use stupid remote controls. :-(

Re:Matirx KVM Switch

[BenFranske]

The CM0264 is dual monitor output, see the description (2x4) though now that I read your description again I see you have 2 dual monitor PCs and not just one so you actually need a 2x5 matrix KVM switch. They're also available (may be 2x6 or something higher) but will probably be quite a bit more expensive. Now that you know what you want exists and what it's called though (matrix KVM) I imagine you can Google it yourself.

Re:Matirx KVM Switch

[BenFranske]

Remember that you don't need to find dual monitor inputs! Because you can route any input to any display you can use two different inputs for connections to a single PC. If you want to use that PC is dual monitor configuration you just route input 1 to output 1 and input 2 to output 2, just ignore the keyboard/mouse inputs on the second input and just use the video switching portion for the second screen. Note that you'll need to find one with at least 2x5 capability though for your two dual output PCs and one laptop.

Re:Matirx KVM Switch

[jez9999]

The problem with something like the CM0264 is that is lumps SCREEN1 and INPUTS into one category that it calls "KVM1" in the manual. So let's say I have CPU1 and CPU4 displaying as KVM1 and V2 on monitors 1 and 2. I'm OK if I want to control CPU1, but what if I want to keep those monitors the same and switch over control to the other computer? I can't see a way to do it. When you switch KVM1 over, it switches the video for SCREEN1 over at the same time.

Re:Matirx KVM Switch

[BenFranske]

Since I don't own one or work for Aten I can't really check that for you but I think that you can do what you want which is to move keyboard and mouse control over to CPU4 but it may require multiple steps of switching things around. They are pretty clear in the manual that either screen can have KVM focus so you can flip KVM focus to the other screen and the two systems flip screens and then you can reassign the CPUs back to the original screens as you want them. Sure it's a pain but you're asking for something pretty unusual to begin with. You may be able to find something a lot more expensive that does exactly what you want or you could live with something like this which does what you want but maybe not as efficiently and for a lot less cost.

Re: Matirx KVM Switch

[amxcoder]

Upon looking at your requirements again, you would need a larger matrix than I originally mentioned. Since you have 3 PC's total, each with 2 monitor outputs, you would need at least 6 inputs. This puts your matrix size in the 8x4 range (don't think you'll find a 8x2). This would bump the cost up depending on price.

I deal with Pro-grade gear for work, so I would suggest something along the lines of an Extron DXP 84 HDMI; or maybe a Kramer brand, or Atlona. I'm sure there are other options that may be cheaper, but can't speak to their quality. Most of these Pro grade models are also RS232 and Ethernet controllable, so if you know a bit of code, you could rig something up and send easy telnet or serial commands to make things a little more automatic to select your "scenes" that you described.

Re:Matirx KVM Switch

[jez9999]

They are not matrix KVMs.

Re:Matirx KVM Switch

[jez9999]

The one you link to is not a matrix KVM. It will only switch dual screen inputs out to two screens, but it will not provide the option to display an input from one display on one monitor and an input from another display on another.

Re:Matirx KVM Switch

[jez9999]

OK just FYI everyone, I went ahead and bought a CM0264 and... it doesn't disconnect the inputs of the video channels that aren't currently selected. So basically it's the same thing as plugging the video cables directly into monitors with multiple inputs. Not such a great recommendation there.

Re:Matirx KVM Switch

[BenFranske]

Disconnecting the inputs would be unexpected behavior... Most good KVM switches do not do that because it causes the system to reinitialize the video output each time which can present it's own set of issues, hence the popularity of EDID devices like the "DVI Detective". I think you'll have a hard time finding a KVM device (particularly a good one) which does not do EDID management. What's unclear is why this is a problem in your situation.

Re:Matirx KVM Switch

[KVM Guru]

This is why I suggested to you the UDD-14A+ It does everything you want it to.... Check out this video https://www.youtube.com/watch?... It shows the two port version....

Re:Matirx KVM Switch

[jez9999]

OK well I've gotten it working quite well now. It's slightly annoying because if it continues presenting the video channel, my dual-screen PC or extended laptop won't drop out of 2 screen mode even when I'm not displaying one of those screens anymore. However I can quite quickly just tell windows to switch to one screen with a couple of "Win+P" keyboard presses.

I've also gotten USB to switch nicely between the different PCs, by *not* using the designated "keyboard" and "mouse" ports on the switch, but just by plugging them in to the "regular" USB ports which can be switched separately (the designated keyboard and mouse ports are undesirably switched with monitor1 and strangely they don't even seem to work properly). The PC rediscovers the USB keyboard and mouse each time I switch but it seems to work pretty well and quickly.

Re:Matirx KVM Switch

[jez9999]

Unfortunately ConnectPRO are very US-centric and being in the UK I don't think ordering from them would be an option, and even if it was they would probably send me a US plug instead of a UK one. :-)

Re:Matirx KVM Switch

[KVM Guru]

You should try contacting them, they do have international plugs. http://i.imgur.com/A1uYZk2.jpg

Is it worth doing this in hardware?

[damn_registrars]

You could use VNC, teamviewer, or anything along those lines to accomplish what you want without throwing additional hardware into the mix.

Re:Is it worth doing this in hardware?

[BenFranske]

Yes, except if you care about latency, etc. I'm assuming this user knows what they're talking about and has specifically requested a KVM for a reason. For example trying to do graphic design work, video editing, CAD, or a lot of other things over VNC or any screengrabber is not really feasible. Even just typing a word processing document is a bit of a pain with the lag...

Re:Is it worth doing this in hardware?

[DarkOx]

If the systems are headless though that might be problematic if one won't boot or he needs to do something outside a software environment that can support those things.

He might also look at Integrated Lights Out Modules. That way his controls are not dependent on the host OS.

Re:Is it worth doing this in hardware?

[unrtst]

IMO, I'd forego the expensive matrix KVM's as well as the loggy VNC-like solutions.

Many monitors support multiple inputs. If yours doesn't, get some that do.
Use the monitors input switching for video input changes. That takes care of video (I'm pretty sure 3 inputs each is more than feasible).

For the keyboard and mouse, use any of the existing hardware solutions for those (there are old manual switches that work with PS-2 and AT stuff that are dirt cheap, and would do the job, for example). Alternatively, use something like synergy (http://synergy-project.org/)

Re:Is it worth doing this in hardware?

[ArmoredDragon]

I've never had latency issues with Guacamole.

http://guac-dev.org/

Re:Is it worth doing this in hardware?

[omnichad]

Except they're wanting the computer multi-monitor support to drop those monitors as unconnected when they aren't visible (or so I assume). Otherwise you could just use a separate KVM switch for screen 2 and have all the inputs on KVM 1.

Re:Is it worth doing this in hardware?

[i_ate_god]

I have three computers connected to two monitors and one set of keyboard/mouse.

I use a tool called Synergy to share my keyboard/mouse across all machines.

The upside is that it's super simple, low latency, and free (though I did pay the $10 the dev asked for because it's such a great tool)

The downside is that I need the computer hosting the synergy server to be on. But this has not been a downside for me.

http://synergy-project.org/

Re:Is it worth doing this in hardware?

[rwa2]

It is worth doing in hardware, if the hardware is simply adding another monitor, and perhaps even a VESA mount. KVM switches aren't cheap. Or if they are cheap, they're not very usable. That said, I've had good experiences with the Aten DVI KVM switches... much better than the driver issues I've run into with Belkins and stuff. The separate USB routing is very useful too.

TigerVNC / UltraVNC is actually very usable with full-screen screengrabbing, especially on a LAN. It can maintain maybe 5 fps, which won't be great for gaming or FMV, but is good enough for most CAD / CAM work or image processing.

I would mainly just use Synergy to extend my mouse to additional PCs over the VNC protocol, though. Again, this won't work as intended for some mouse actions (like click and drag to rotate), but it beats the frustration I get when trying to remember which KVM switch setting lets me control which PC. I'm much more sane juggling separate keyboards and mice, which are much cheaper, and just about every desk I've seen has extra keyboard trays so space has never been a big issue.

Re:Is it worth doing this in hardware?

[vivian]

I use Synergy too - and the multiple inputs of my monitors to allow reconfiguring of which PC has two screens.
eg. Linux 1 running linux on the left, workstation in the middle with two monitors connected with DVI cables, laptop on the right with Windows.
Each screen has an HDMI, DVI and VGA port - switchable by pressing the input button on the screen.
Each laptop is also connected to the closest monitor, using HDMI cables.
Synergy server runs on the workstation, with the mouse and keyboard connected to it.
Each laptop is a synergy client.
so all together 3 pcs, 4 screens, 2 different operating systems.

I can flip between using a single screen or dual screens with the laptops, (which of course means using only a single screen or no screens for the workstation)
in practice, I don't usually need to bother dual-screening with the linux laptop, as I tend to use it's screen to edit files on the workstation anyway, or just use it to browse documentation on the web - but I do find it useful to sometimes dual screen the windows laptop at the expense of one of the workstation screens, such as when I am doing a lot of windows development and debugging. Of course if you have 3 or 4 monitors it's easy to just insert that in the mix and not have to flip screens at all - and if you have a few more old crusty laptops or a mac or something they can very effectively become part of this setup by just adding them as additional Synergy clients.
The only downside is that if you have the laptops set up in multi monitor mode when the workstation has use of both screens, you have to move the cursor across the 'hidden' screen - but of course you can just switch back to single display mode for the laptops if you aren't going to be switching displays back and forth much, and you get used to the 'blank' spot (in the mouse's travel) pretty quick .

Of course you can also copy and paste text back and forth between all three machines, which I don't believe you could do with a traditional KVM setup.
On Linux, as soon as my laptop wakes (from sleep or hibernate) , it happily reconnects to this config, and works without having to reset anything.
Unfortunately with Windows, sometimes when it comes out of sleep, you have to stop and restart the synergy client for it to reconnect, though it seems to have fewer issues with hibernate.

You can also layer in something like VNC or remote desktop into this mix if you need to connect to additional desktops too, of course - but the main thing is you have a whole lot of screens, a whole lot of PCs and only one keyboard and mouse to rule them all.

Total cost: $0
Utility: priceless

Workstation:

Re:Is it worth doing this in hardware?

[jez9999]

Exactly. When the monitor changes inputs, the other PCs still think they're connected to the monitor and so if they're in dual-screen mode, they won't automatically drop back to single screen mode. Unless there's a monitor that tells the PCs whose inputs aren't selected that the monitor has been disconnected, this will be an annoyance.

Re:Is it worth doing this in hardware?

[omnichad]

I'm sure you could get a KVM that doesn't have a dummy load on the non-active display. But that's only a small part of the battle.

Re:Is it worth doing this in hardware?

[dahlellama]

+1 for Synergy.
My setup is one laptop on a dock and one PC all hooked up to three monitors. (One dedicated to the PC and the other two connected to the dock.) My PC is running Windows and my laptop is running Linux and they get along quite well.

Since I use it at work, I payed the $29 for the encrypted version. No one is going to sniff my keyboard data. ^_^

Re:Is it worth doing this in hardware?

[jez9999]

Why's it a small part of the battle? I'd say the video setup is the hardest part.

Re:Is it worth doing this in hardware?

[omnichad]

Because they still want monitor 2 to possibly point to monitor one of another machine. So monitor 1 of any machine has to be routable to either display. If I understand right.

Re:Is it worth doing this in hardware?

[jez9999]

The original point being made in this thread was that the monitors would be connected directly to the PCs, and the monitor inputs would be changed to achieve single or dual screen capability. That would solve the video issue without the use of a KVM (but as mentioned before, the problem would be that the monitor would still tell the PC that it was connected even if the input was not set to that PC).

Re:Is it worth doing this in hardware?

[unrtst]

... but as mentioned before, the problem would be that the monitor would still tell the PC that it was connected even if the input was not set to that PC..

I was not aware of that behavior (I haven't tested it myself).

That said, there are simple software solutions for that:
* man xrandr
* man nvidia-settins ... etc for GUI tools. Should be fairly simple to disable the display via software.

Maybe not ideal, but how often are they really going to be swapping around the displays? If it's more than a couple times a day, then I'd imagine that the desktop layout reconfiguration (from 1 to 2 screens and back) would affect workflow more than it would be worth... just connect a "main" desktop, and vnc (or similar) to the others as needed for quick-swap needs, and do the full change only when necessary.

just put everything in VM's

[Anonymous Coward]

just put everything in VM's

and in the darkness bind them

Re:just put everything in VM's

[Culture20]

just put everything in VM's

You could use Linux KVM for that! Not to confuse the issue...

really necessary?

[nimbius]

Basically with the latter two modes I'd like to be able to switch between inputting to PC1 & DOCK1, whilst continuing to be able to monitor each by outputting each one's video to one of the 2 monitors. However, I also want to be able to go dual-screen with and control PC1 & PC2.

I guess a better question is 'what do you want to do?' It sounds like all 3 will need to be immediately accessible. switching quickly between the 3 would be cheapest if you purchased multiple keyboards, and mice. Identify the gaming machine, and if required give it 2 monitors. the rest can KVM traditionally through a single or have a dedicated number of monitors.

workload in general...you might want to address some consolidation issues if you find yourself requiring 3 graphical terminals. For example: if one is a BSD machine you could simply ssh or vnc into it.

Re:really necessary?

[jez9999]

Multiple keyboards and mice are an option as a fallback but I'd really like to avoid that as it's going to use up way more desk space.

Consider alternatives

[davidwr]

While you may actually need this consider cheaper alternatives:

1) Use software remote-desktop/remote-screen to take care of use cases 3 and 4. This may or may not work for your use cases.

2) Have additional monitors and monitor-mirroring hardware to mirror PC1 and DOCK1 "all the time" to take care of use cases 3 and 4. This may or may not work if you have limited desk-space to work with.

Re:Buggy things

[elfprince13]

Yeah, I don't understand how it's possible that they're as bad as they are, on especially on the HID side. My CODE's media keys don't get sent through my KVM even though my crappy Logitech's do.

Hmm yes a matrix switch,, but.....

[Anonymous Coward]

Whats the purpose of this exercise??

if I had a better understanding of why, then I could better provide the correct solution..

I hope it's a real business use case versus "ya know it would be cool if....."

Synergy + Monitor Inputs

[fsh]

I do something similar to what your looking for with a combination of Synergy (http://synergy-project.org/), which uses your network to send the keyboard/mouse inputs to the correct computer based on your mouse position), and multiple inputs on my monitors. In other words: PC1 would be your base computer, and would have the keyboard/mouse you want to use with everything attached. PC1 would be attached to the primary port of both monitors (HDMI, for instance) PC2 would also have a keyboard/mouse, but they wouldn't be used. It would be hooked up to the secondary port of both monitors (maybe displayport) DOCK1 will obviously have the laptops built-in keyboard/mouse, but that wouldn't be used. It would be hooked up to the third port of both monitors (maybe DVI or RGB) In this setup, you'll need to manually change the monitor inputs, and synergy will direct the keyboard/mouse to the correct places. As far as I know, your only other option would be the matrix KVM (as mentioned above a few times)

Re:Synergy + Monitor Inputs

[funwithBSD]

Synergy automatically handles these edge cases. When I plug my external monitor in, synergy does not care if the laptop screen keeps working as screen 2, or everything goes to the external.

If I unplug one of the two monitors attached to the PC, Synergy still does not care.

I have even had 3 set up, and attach mouse to the one that won't move, and place the others on either side. That way, if they are missing, it does not cause any problems.

What does not change is the boundary. If I used both monitors and it is "taller" than the other screen you have to move the mouse to the lower screen before sliding to a side to change computers.

Re:Synergy + Monitor Inputs

[silas_moeckel]

Synergy and a matrix hdmi switch gets him everything he is looking for.

Re:Buggy things

[ArmoredDragon]

It really depends on the monitor (some monitors are really bad at handling disconnecting/reconnecting digital inputs without a power cycle) the mouse/keyboard used (sometimes they flake out when disconnected and reconnected quickly) and most importantly, the drivers. Shitty drivers can easily cause hardware to become unresponsive when you do a quick disconnect and reconnect, which is what a KVM simulates.

For one, synergy...

[Junta]

It may be best to figure out a way to wire up your monitor multiple inputs up to the various desktops, and using the monitor input switch buttons. For the input, synergy (http://synergy-project.org/) which I haven't had use for in a long time. Otherwise, just have some close at hand usb hubs close and move the cables around. There exist 'cleaner' KVM devices to do this, but they are way expensive. If your monitor inputs are lacking, new monitors are likely cheaper than the KVM device you would need to not get new monitors. Monitors with three digital inputs would probably be the easiest thing to meet the requirements verbatim.

For another, I'm really wondering why you feel this need so strongly. What tasks are you spreading amongst all these systems? How many of these tasks *really* indicate need for directly using the attached 'head' versus remote access (RDP, VNC, ssh, whatever). Is there a good reason that the things that really need direct connectivity can't be grouped into a single system? If not a single system, narrow down to 2 PCs and comfortably fit on your monitor inputs.

Re:For one, synergy...

[ChromaticDragon]

The one thing missing in this description is requirements for and/or support of networking.

I've wrestled with stuff like this. I agree with all folk suggesting VNC, RDP and the like. If these can meet the need, then I bet the end experience will be better. Cheap KVM switches suck.

But, there's one simple thing that can render this unsuitable: VPN requirements. Several VPN clients are designed to shut off all other networking while initiating the VPN session. This will kill all these solutions that depend on local networking. So if one or more of his machines are essentially used to access separate VPNs, he really may be stuck with KVM-like solutions.

If this is the case, there may be one other solution. I was very pleased when my company switched VPN clients and I could finally have concurrent networking. I ditched my KVM switch. Now they're switching VPN clients again and supposedly the laptop will be locked down again. The solution here is to switch to a VM on said laptop and run the VPN client from within the VM. Now that we're going VM though, why even turn on the laptop? Well, if you will need to travel, you do want the laptop ready to go. So, keep the VM on the laptop. But for the OP, with just one laptop, I have to wonder if one of these desktops couldn't be folded into a VM on the second.

Re:For one, synergy...

[Junta]

Given modern monitors and the reality of USB, the worst case for non-KVM is hit input select on two monitors and move a single usb cable between three ports. A fancy KVM is pretty expensive to save the trouble of moving a cable and one extra button press.

Re:For one, synergy...

[gstoddart]

Until you factor in the time it takes, the nuisance it introduces, and the chance that over time your USB port suffers additional wear and tear.

I mean, you've added nothing of value here ... you might as well have said "why, gee, why not just have a whole second desk and walk over to it?"

Clearly the poster has some specific use cases in mind. And I wouldn't waste my time moving USB ports for the two computers I have on KVM, let around mucking around with it for several computers and monitors -- the more pieces there are the more it becomes a pain in the ass and a waste of time..

As a grumpy old man who sometimes sees a lot of technology as pointless, even I look at your response and think "yeah, let's not do it that way".

HP-RGS: better than RDP/VNC & simpler than KVM

[kyubre]

I spent about 6 months working on this product last year:

http://www8.hp.com/us/en/campa...

HP's RGS is really excellent remote graphics solution, suitable for the likes of film production studios and CAD/CAM design firms - at 4K resolutions and 30FPS video. It all sports support for a plethora of input devices from Wacom tablets to speciality LogiTech mice. To top it off, its bidirectionally compatible with Windows and Linux and Mac can be coaxed into working as well.

Regular KVM plus HDMI switch

[Guspaz]

The complexity seems to be wanting to swap inputs between split screens. If you give up that requirement, and simply say that input is tied to screen1, then there is an easy solution: a regular KVM for screen 1 with the first video output of each computer, and a simple HDMI switch on screen2 with the second video output of each computer.

Whatever computer you put on screen1 controls it, and you can then set screen2 to whichever computer you like.

Me too

[Tailhook]

I've looked at some expensive KVMs, software control of display inputs and other stuff. Bottom line is no, there isn't a good solution of this. There are a bunch of limited, glitch-prone things you can do, but what you're thinking of doesn't exist yet.

My expectations for such a system are as follows; connect an number or computers (3-4 minimum) in arbitrary ways to a number of displays (4, minimum) and a set of input devices, without a.) lag b.) glitches c.) limitations on resolution, refresh, etc. Lag can be no more than a few imperceptible microseconds. Glitches include input devices not being recognized, causing hosts to have driver conniptions when switching, displays not getting signals, and other typical KVM behavior. All of this must happen using a single button press to switch among programmable configurations, and configuration done with a high quality native GUI on whatever platforms I happen to be running. Oh, and audio.

Modern displays usually have multiple inputs, and some of them even have non-shit firmware that switches between inputs quickly and without a bunch of mode-setting drama. The problem is there isn't a good, universal way to control this from software. There are some creepy, half-supported utilities floating around in freeware/shareware land that work with some displays. Barring that the current state-of-the-art is wearing out the input select button on a display you may not be able to reach...........

I wouldn't hold your breath either. Its going to take a few more years before it dawns on manufacturers that the desktop market hasn't actually died. Right now they're in table/laptop/phone mode and — aside from g-sync and other gamer stuff — there isn't much innovation going on with desktop hardware.

If you're willing to be very selective about your hardware and spend some money, particularly on your displays, you can almost get there. You'll need an active USB KVM system like ConnectPro, displays with a generous number of software controllable inputs, and you'll need to be to be prepared to deal with all the sundry glitches your creation with make you suffer.

Use the KISS Principle

[Digicrat]

I used to have a similar setup at my old place (though without a dock for the laptop, and adding a TV as an occasional tertiary display). While I agree that some sort of smart KVM would be ideal, this is a case where it's best to keep it simple. There's no need to spend $$$ when all you need to do is be smart about what you connect, and press a few extra buttons to switch displays.

My approach was something as follows:
- 4 Port KVM Switch (USB-capable, $20 from newegg)
- 2x Monitors, 1x TV, 2x Desktops, 1x Laptop
- All computers connected via USB to KVM for switching keyboard/mouse. If I were to do it today, I might bypass the KVM and setup QuickSynergy on all machines instead, or in addition.
- Right monitor connected to KVM to switch (VGA) between Desktop 1 secondary display and laptop external output
- Desktop primary output connected via DVI, one to left monitor, one to right monitor
- Desktop 2 secondary display via VGA to left monitor and Tertiary DisplayPort to TV

Both desktops always output to both displays, but each used a different monitor as its primary. I could use the monitors source buttons to quickly switch either monitor between inputs, with the KVM on the second monitor enabling a 3-way switch between the 2 desktops and laptop.

At one point though I actually got annoyed with the KVM, and just used the laptop on its own, and kept 2 sets of keyboard/mice on the table (one for each desktop).

The one feature I wish I had today, was eye-tracking/mind-reading software that automatically switched my keyboard/mouse to the computer+display I'm looking at.

Certifiable

[PopeRatzo]

But here's the kicker; I'd like at least 4 modes of operation: one mode to output PC1 video to both screens (dual-screen) and redirect INPUTS to it, one mode to output PC2 video to both screens (dual-screen) and redirect INPUTS to it, one mode to output PC1 video to SCREEN1, extend DOCK1 video to SCREEN2, and redirect INPUTS to DOCK1, and one mode to output PC1 video to SCREEN1, extend DOCK1 video to SCREEN2, and redirect INPUTS to PC1.

You don't need an advanced KVM switch, you need medication.

Why spend money to keep an old computer relevant?

[0xdeadbeef]

Just do what I do, get one of these, and use monitors with at least three inputs. There's actually quite a few that do DVI, HDMI, and either Mini DisplayPort or VGA.

But oh noes, you'll have to change the monitor inputs individually. No KVM is going to let you swap them independently of the keyboard/mouse, at least not one that costs less than a whole computer, which poses the question - why are you fetishizing your laptop? What can you possibly run on it that won't run on the desktop PCs? And if it is so important, why not give it a dedicated monitor?

Two KVM switches.

[harrkev]

It sounds to me like you need TWO kvm switches.

One with a keyboard and mouse attached to it, and one monitor. The other would be just video -- or you could even use a cheap HDMI switch for this one.

This would allow you to have the keyboard and mouse tethered to one monitor, while the other monitor was independent.

For extra-fancy operation, you could even use an HDMI splitter to have the same video input going to both switches, if you needed to.

The only down side is two separate boxes to control, but you could probably rig up an Arduino or something to keep them flying in formation.

Re:Why spend money to keep an old computer relevan

[gstoddart]

But oh noes, you'll have to change the monitor inputs individually.

Hmmm ... but how often do you do it every day?

I've got two monitors, two computers (laptop and desktop), and a cheap Belkin Flip KVM -- not nearly as complicated as the poster. My laptop is work, my desktop is my own stuff.

My laptop is on the left, and when I use the KVM the middle screen mirrors the main screen of the laptop (bigger, and right in front of me), or is the left screen of the desktop -- the right screen is always my desktop's right screen.

I switch between by desktop and my laptop about 40-50x/day ... all with one button.

Even for my simple setup, having to change my monitor inputs manually would add a crap load of extra time.

How many button presses does it take for you to change inputs on the monitor? If it's more than 1 is starts to become cumbersome. If it's more than 2 it's probably tedious. If it's more than 3 it's probably annoying as hell.

A cheaper workaround

[vux984]

I suggest 1 cheap kvm, 2 hdmi switches, and a few hdmi port mirrors.

kvm1 manages your keyboard to input...

1 - dock input
2 - pc1 input
3 - pc2 input

hdmi switch 1:

dock video1 to screen1 left splitt
pc1 video 1 to screen1 (left split)
pc2 video 1 to screen 1 (left split)

hdmi switch 2:

dock video 1 to screen2 (right split)
dock video 2 to screen2
pc1 video 1 to screen2 (right split)
pc1 video 2 to screen2
pc2 video 1 to screen2 (right split)
pc2 video 2 to screen2

This setup lets you put any video 1 on the first screen, and any video1 or video2 output on the 2nd screen.

Ideally you'd want hdmi selectors with direct selections (a lot just have one button) that you push to cycle. Some also have remotes... you probably don't want multiple remotes, but pair the above with a programmable remote, and you could probably set it up so that you can switch screen confiugurations with one button. (and then set the usb input separately...)

not ideal; as its a bit more work to switch configurations but its doable for under $200, give or take; vs several hundreds to thousands for a matrix kvm.

Alternatively to that, I'd suggest software solutions. Making one unit the master, and then remoting into the other two various ways to accomplish what you need. Remote desktop / VNC / NX Machine ... etc. There are all kinds of solutions, cross platform, multimonitor support, etc...might work for you unless you are doing gaming or video editing.

-cheers

SingleKVM Cheap Solution

[ANIMUSX]

You can use a Dual DVI, 4 port switch like SV431DD2DUA (which is cheaper then ATEN ). Hook up the MON1 and MON 2 to the outputs of the KVM. Use a 3 way splitter for the DVI of PC 1: INPUT1 PORT1, INPUT1 PORT3 and INPUT1 PORT4, The PC 2 is a straight connection to each of the DUAL DIV INPUT1/2 PORT2, Connect the DOC output using a splitter to INPUT2 PORT3 and INPUT2 PORT4. Connect the USB out from PORT1 and PORT3 to PC1 Connect the USB out from PORT2 to PC2 Connect the USB out from PORT4 to DOC. Now ports 3 and 4 have same video inputs and 2 different USB inputs. The audio can be source switched using Hot Keys. Easy peasy.... Good Luck

Spit and duct-tape...

[pla]

Cheapest solution possible (short of just going with VNC), and arguably the most flexible as well:

1) Get a normal 4-way KVM switch for your mouse and keyboard.
2) Get two monitors that support three inputs each (most do anyway these days).
3) Make sure all your PCs/laptops support dual monitors (again, almost ubiquitous).

Then just use the monitors' source selection to pick what you have on any given screen, and the dirt-cheap normal KVM to pick which box gets to have a keyboard.

Quite likely, your existing hardware already supports all of what I describe, except needing the el-cheapo KVM for kb/mouse.

Re:Its all about goats and cabbage

[rjstanford]

Finding the correct answer (goat, nothing, wolf, goat, cabbage, nothing, goat) is far easier than figuring out what fiendishly complex business problem the OP is trying to solve here that wouldn't be more easily solved in a different way. Of course, since useful details are rarely provided, we'll probably never know.

Re:these questions irk me

[rjstanford]

There's probably a better way to solve the actual that some of you could come up with if I told you what I was really trying to do, or gave you any hints like a useful budget amount or how often each case came up, but I don't want to feel too silly so please just figure out this one piece in isolation.

This isn't a normal KVM solution

[NimbleSquirrel]

Are the point you want to separate displays between two machines, you deviate from what KVMs are designed for. It comes down to what you want to spend. I'd suggest you get an HDMI matrix with at least 5 inputs (PC1 1&2, PC2 1&2 and Laptop) and 2 outputs (screen 1 & 2), and then get a separate USB switch. Finally you need control to link them together (unless you really want to switch them manually). If you get IR controllable HDMI matrix and USB switch, something like a Logitech Harmony should easily control both. Then you just customise whatever modes you want.

THIS, x1000... with caveats...

[tlambert]

Wont work unless the HDMI matrix has EDID management so the computers do not see the displays appearing and disappearing.

You need a good quality one, not the junk from monoprice. About $1100 for a good 4X4 with full edid management.

THIS, x1000... with caveats...

The caveats are:

(1) Many monitors won't negotiate an EDID on an inactive channel (i.e. one not selected as the primary channel at the time the computer attempts to negotiate). This is mostly because the firmware in these monitors is not running a finite state automaton and/or is not multithreaded, and so ignores channels which are not currently selected when negotiating. A *lot* of monitors and television sets being used as monitors, particularly Samsung models, have this problem.

(2) When using left/right or top/bottom negotiation, your KVM needs to present EDID information for the effective aggregate monitor size for the negotiation. And most KVMs, even those with EDID management, can't do that. In other words, the KVM has to present one *or more* monitors to the computer as if they were a single, higher resolution monitor. Right there, you've blown the price of the KVM hardware out of most price ranges. Even then, you may find that the KVM suffers from the same "inactive channel negotiation" problem described as a monitor problem in #1.

(3) Most operating systems fail to implement active resolution renegotiation. This is a problem in two ways:

(3)(a) For the proposed use model, when doing mode switching, i.e. when switching between which PC "owns" a given display, the EDID management that negotiated with the OS over the display resolution is no longer valid... the virtual resolutions may have changed out from under them, based on what the EDID management presented as possible display resolutions, vs. what the monitors that ignored the KVM because it wasn't currently active present as the possible resolutions, vs. the difference between presenting one monitor, or more than one monitor, as the virtual monitor.

(3)(b) The OS renegotiation problem may prevent it from working anyway. Specifically, a lot of "media center" PCs are built on top of Linux, and Linux is really poor at renegotiating an EDID with a device when it goes from the "device not connected" to the device connected" state. This problem tends to find itself exacerbated by the fact that a lot of (stupid) monitors will not switch to a non-default input channel, unless they see that there is active input on the port.

Apple products (*not* Hackint0sh!) tend to have much fewer problems in this regard; Windows, it really depends on the hardware (Toshiba tends to be bad; Sony tends to be better at it), the video driver (which depends on the card in use), and which version of Windows.

P.S. Linux really needs to fix its EDID negotiation on these axises -- but FreeBSD is generally worse, even though both these platforms inherit their EDID negotiation from their windowing systems.

Just use two KVMs

[thecombatwombat]

One has the KVM, the other just switches monitors, done. You'd have the inputs tied to only one monitor at all times, but would that really matter? Instead of extending the dock to display two and redirecting input, you'd extend it to display 1 and redirect input. Cheap and easy.

This seems to cover the "basically I want to . . . " part of the original post just fine.

2 cheap KVMs

[ChaseTec]

All three of your computers have dual monitor output. You have 2 monitors.

Put a 3+ computer KVM on each monitor, connect each computer to both KVMs.

The only drawback is you would have to press buttons on KVMs to change you modes, you wouldn't be able to use the keyboard shortcuts keys that some KVMs support.

Virtualisation?

[Qbertino]

Sound's to me like you're ready for virtualisation at a professional scale.

Why don't you just swap all your PC trinkets for one single extremely powerfull box and a single big fat screen and virtualize all the rest?

And with powerfull I'm talking 3+GHz Quad-Core i7, 32GB of RAM and a 1 TB SSD or something.
And by big screen I'm talking extra wide, as in, seriously *extra* *wide*.

I'm using a pimped out Cirrus 7 Nimbus, which has those sort of performance specs and runs completely fanless. ... And it's pretty small and not even that expensive.

Conclusion:
Before you spend a large sum on a special KVM solution, you should definitely consider a professional VM setup on a single machine. ... It's 2015 - you get supercomputers of the shelf, on a shoestring budget these days. It may be just a a few hundred dollars more and way more future safe. ... All my KVMs from back in the day are collecting dust in the cellar.

I've done the next best thing for ~$5:

[ChoosyBeggar]

I've got a similar setup: 2 HDMI monitors, (TVs, actually,) 2 desktop computers, and a portable in a doc.

The two desktops are each display out to the two monitors.
The dock outputs to the main monitor.
I also have a 4-port USB SWITCH, (a cheap, Chinese model, ~$5,) with push-button selection, connection a USB-hub (keyboard, mouse, etc) to each computer (& the dock.)

With no further expense, switching controls and monitors is very simple, albeit with two commands on two controls.
I imagine I could make it a single physical push-button action to select from 4 distinct, "programmed" modes by adding a programmable IR emitter to the USB-hub...

Re:Futile

[nabsltd]

USB isn't built for juggling machines. Every time you switch from Machine #1 to Machine #2, the USB devices all magically vanish and disconnect from Machine #1 (prompting drivers to be disabled), and magically reappear on Machine #2 (drivers now have to be loaded and initialized).

Good KVMs show up as a composite HID device and always present that to the OS, even if a different computer is now active. One of the things this means is that most gaming mice and some keyboard keys aren't passed through.

Really good KVMs have an option to disable this feature and allow straight pass through of the devices to allow all functionality.

Monoprice KVM

[MoarSauce123]

Unless you want to drop hundreds of Dollars for a matrix switch take a look at the 3 PC Monoprice KVM 131DA. I use it with great success. It can switch most inputs separately, but supports only one DVI channel. I looked into dual screen KVMs and while they exist they are prohibitively expensive. I connected the second monitor on one PC directly via DVI and from the second computer directly via VGA. The VGA from the third computer goes to the first monitor, but I very rarely use it because both signals go to the same monitor. What you could do is get two of these switches and control one via keyboard and the other one simply with the push buttons on the switch. That way you can switch plenty of combinations. It is not as convenient as having it all in one box and use programmable hot keys for switching the setups, but there is always a limit to how much one is willing to pay for just a wee bit more convenience. Unless I watch TV/movie, work on large projects, or work from home I do not use the second monitor. You may also want to look into other options such as remote desktop solutions. Not sure if the free options are sufficient, but with selecting which monitor you want to show up from the remote systems you may get what you need. Add a USB switch so that you can share USB peripherals.