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Here's the situation, there's a small server room in our office (~4 active servers), but only one monitor/keyboard. Currently monitor and keyboard are connected to the most used server, but if the need to diagnose a different box would arise, I'd have to reconnect them manually.

Is there any (preferably cheap) solution that would allow me to switch to what server monitor/keyboard is connected without physically reconnecting them?

Monitor + Keyboard | | periferial switch | | server1... server2...

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up vote 8 down vote accepted

A KVM switch (Keyboard, Video or Visual Display Unit, Mouse) is a hardware device that does exactly what you need, that is allows you to control multiple computers from a single keyboard, video monitor and mouse.

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That's exactly what I needed to know. Thanks. – Karolis T. Jun 15 '09 at 10:28

Google on "KVM switch." There's plenty to choose from in every price range. Watch out for the models that require so-called "dongles" to convert the standard USB and video ports from your machines into a adapter plug that the KVM accepts. Usually these are used to help you add distance between the computers and the KVM switch, such as the type that convert the signals to a format that can be transmitted over CAT5 cable. If you can't (or don't want to) keep the KVM close to the machines, you may end up spending more for cables than for the KVM itself. Shop around. Belkin's been around quite a while. Black Box is also an old-timer in the low-end arena.


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For this situation any popular brand 4 port KVM (Keyboard/Video/Mouse) Switch such as the provided by Belkin or APC would work well for you, I recommend getting one with an external power supply some cheap KVMs without a power supply can draw too much current from the PS2 ports, not had any problems with unpowered Belkin or APC for what it is worth.

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While Scott's concern about the added cost of cables for the "dongle" type KVM are valid, they do bring a couple of advantages. We use Advocent KVMs and as they use a dongle that takes the VGA&USB&PS2 connectors and converts to Cat5 type cable, I can make the Cat5 cable the length I need. Cat5 cables probably fit into your cable management system on the racks better than the bulk KVM cable. Some "Non-dongle" type KVMs still require special cables, which brings in the same cost considerations that Scott mentioned.

Another feature to look at is KVM over IP. Basically you can assign an IP address to the KVM, and get to it via a web-browser. This means that if you want to reboot a server, and the boot hangs for some reason, the IP KVM can save a trip to the server-room. Combined with VPN, and I can reboot a server and change BIOS settings from home.

A word of advice, practice using the KVM BEFORE you need it. You don't want to be learning which button swaps servers, or any quirks in the interface while troubleshooting a down server!

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