10 ms·

KVM switches used to be a huge and super important (and expensive) thing in rack server farms back when every rack or every few racks had a pull-out tray with a

by sdfjkl 9y ago

KVM switches used to be a huge and super important (and expensive) thing in rack server farms back when every rack or every few racks had a pull-out tray with a keyboard and a monitor. Technology moved on. First the tray and monitor disappeared with KVM-over-IP, which saved many trips to the server room. Then the KVM switches themselves disappeared, as manufacturers integrated out-of-band remote access into the servers, first with add-on boards, then onboard and finally on-chip (this is what Intel AMT does, when it isn't busy running rootkits). The little two-PC switch box the article refers to (I think) was always a spillover from the server KVM technology, except with a very small market and more difficult to make. Servers don't need sound and are fine with just VGA video. Home computers want USB (which variety?) and audio switched, or high bandwidth signals that are very touchy about interference or suddenly being connected to a different device like HDMI, Displayport or Thunderbolt. And then people want the stuff for cheap. > signal switches with arbitrary bandwidth remain available: analogue relays Have you tried that? Cut a HDMI cable in half and splay it out, then try switching that to another display. See what happens. If it were that easy, it'd be around (or you'd just be building it yourself).

fraqed 9y ago
As well the use of KVMs by PC enthusiasts has most likely been replaced by virtual machines.
OliverJones 9y ago
Yes, no doubt that rack-based kvm stuff disappeared. It was awful: hard to rig, hard to use with confidence. (Confidence? "Wait, wait, am I talking to data2 or web4 or what?) KVM was a just-barely-competent solution to a hair-on-fire (=== must-solve-now) problem.
- NameOpenSource 9y ago
  "What ? this was the production server ?... woops"
gambiting 9y ago
The easiest solution is to just buy an HDMI switch(there's loads of them, even ones which work with 4K signal, and they don't disrupt DHCP) and a USB switch. Total solution should fit in about 40-50 dollars.
- Jaruzel 9y ago
  But, that's more than one button to push! /s Seriously though, I am a regular user of DVI and VGA KVMs, which have served me well over the years, but now as I migrate to HDMI or DisplayPort connectors and higher resolutions, I'm finding myself having to re-think how I hook everything together.
  - petecox 9y ago
    My windows laptop has only VGA out, so I hook up a second monitor via displaylink (usb -> DVI). I tried plugging the cable into my KVM switch and it worked okay on the Windows 10 side but there was some hot-plugging kernel panic when switching to Linux (must file a bug report!) So perhaps the future of KVM switches doesn't need video connectors such as VGA/DVI/DP if USB-C -> HDMI (as smartphones are adopting) becomes universal.
- megaman22 9y ago
  Are there any that don't suck bogwater? We've tried a handful for our conference rooms, and they are all universally flaky, with signal dropping randomly all the time.
  - gambiting 9y ago
    I found that HDMI switches lose signal because the output device doesn't provide enough power for the switch to leach off. I've had a few of Aukey switches: https://www.amazon.co.uk/Switcher-Output-Splitter-Control-Blu-Ray-Black/dp/B071RHDWVV/ref=sr_1_2?ie=UTF8&qid=1512049679&sr=8-2&keywords=aukey+hdmi+switch https://www.amazon.co.uk/Switcher-Output-Splitter-Control-Bl... And once you plug in a dedicated 5V power supply they are rock solid.
Fnoord 9y ago
Anecdotal, I still use a KVM, for a specific use case. My PC has 2 monitors. My 1st monitor is standard usage, but my 2nd monitor is also used by my partner's PC. If she wants to use her computer, she gets the 2nd monitor (and the speakers) but otherwise I got a 2nd monitor to use. Practically, it saves me from having to use another set of speakers (you would not use 2 sets of speakers at the same time and I usually use headphones) and it also saves me from having to have or use 3 monitors which takes up more space and costs more. My partner doesn't use her computer a lot. When she does, all the hardware is available for her. I use the 2nd monitor during development, gaming, watching movies, and RDP session. As per some comments, I don't see how a VM would replace this use-case but I do understand its niche. Still, it saves us space.
- Jaruzel 9y ago
  You are not alone in this. For years my Partner and I had separate machines on a KVM. It was only when our Daughter moved out and her desk became free in our study that we no longer needed this setup.
  - copperx 9y ago
    You had a daughter with your business partner? I'm now curious about the story.
    - grzm 9y ago
      Partner can be used in lieu of spouse for an unmarried couple.
      - bfhd 9y ago
        Even for married couples!
        grzm 9y ago
        Thanks for the pointer. I wasn't happy with my phrasing. I should have just referenced a dictionary. MW's sense d is what I intended to convey: > "a person with whom one shares an intimate relationship : one member of a couple" https://www.merriam-webster.com/dictionary/partner https://www.merriam-webster.com/dictionary/partner
Jaruzel 9y ago
> Cut a HDMI cable in half and splay it out, then try switching that to another display. See what happens. If you took an ancient (but still available to buy) 25-pin 'parallel port' 4-port switch box with a rotary dial: https://photography-909a.kxcdn.com/product-images/03292/600/03292a.jpg https://photography-909a.kxcdn.com/product-images/03292/600/... And wired up the HDMI of two machines to output ports 1 & 3[1]. Then wired up the HDMI to the display to the input port (so effectively using the switch 'backwards'). As you are just simulating unplugging and re-plugging in the HDMI cable from each machine, via the switch, then surely this would work? There would be a bit of delay after switching as the HDMI/HDCP handshake completes, but unless you are switching every few minutes it should be usable? If it does work, then you've got 6 pins in the switch left to play with which could be used to switch usb devices (via a downstream hub) I've not done this, but have thought about it for a while now. ---- [1] Not ports 1 & 2 as you want to ensure total electrical isolation between the devices during switching.
- gm-conspiracy 9y ago
  I think the real isssue is with HDCP. The output device "ensures" the display device is authorized via a key to output. So, you would need an intermediary device that would accept any incoming signal, while also having a legit handshake with the output device. So, as you switch "inputs", there is no additional authorization required, because the output device does not detect any changes.
  - sitkack 9y ago
    I believe this is also the case. The only organizations that can get exemptions from the HDCP Alliance (DRM Cabal) for devices that effectively circumvent encryption are for high end broadcast gear. Nothing precludes making a 4k KVM. Infact, a mid range AV main unit could probably route 4k KVM. https://usa.yamaha.com/products/audio_visual/av_receivers_amps/rx-a770_u/specs.html#product-tabs https://usa.yamaha.com/products/audio_visual/av_receivers_am...
  - aidenn0 9y ago
    It's absolutely not HDCP since a 4k HDMI splitter is much cheaper than a 4k KVM. My guess is that with KVMs disappearing from server racks, there isn't enough volume to get the prices we used to get.
ghaff 9y ago
I actually bought a 4-port USB/HDMI switch model fairly recently. It's really just a clutter and convenience thing. I have a few computers, including Raspberry Pis, that I just fiddle around with sometimes. While I could do things in different ways, it's just simple to have one monitor, keyboard, and mouse and plug the computers into the switch.
- j_s 9y ago
  Do you have time to link the specific product if it has been working well for you? I personally wouldn't even mind a referral link though most get downvoted, especially if they lack a disclaimer. Something that can reliably connect to random/miscellaneous projects would be really useful to me!
  - ghaff 9y ago
    This is what I got: https://www.amazon.com/gp/product/B06XRDS1CG/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B06XRDS1CG/ref=oh_aui_deta... It seems to work fine although I haven't used it a huge amount.
    - ztjio 9y ago
      This does not meet the requirements of a modern workstation by my or the original article's requirements. This is limited to 1080p. We're looking at 4k as a minimum.
      - Zekio 9y ago
        There do exist some 4K and even freesync capable switches with USB3, I only know of the Level1techs ones Single Monitor https://store.level1techs.com/products/kvm-switch-single-monitor-model https://store.level1techs.com/products/kvm-switch-single-mon... Dual Monitor https://store.level1techs.com/products/kvm-switch-dual-monitor-model https://store.level1techs.com/products/kvm-switch-dual-monit...
deleted 9y ago
[deleted]
arghwhat 9y ago
At work, we have at least the first 30 racks with good 'ol VGA KVM's (no IP) and tray monitor/keyboard/touchpad, despite at least half of the servers having IPMI. Ain't going anywhere anytime soon. And no, no one needs 4k where a KVM belongs (which is in a server room).
- djsumdog 9y ago
  I needed a 4k switch. I had a nice monitor and a Linux and Windows laptop. I used the Win laptop for gaming and the Linux machine for pretty much everything else. Everything I tried was garbage: http://penguindreams.org/blog/4k-uhd-kvm-switches-the-startech-sv231mdpu2-and-the-iogear-GCS62DP/ http://penguindreams.org/blog/4k-uhd-kvm-switches-the-starte... There are a few in the $500+ range I have not tried, but you are wrong, there are use cases for 4k switching. I mean, do you really want to have two 4k monitors next to each other when you could just have one for half the cost?
  - fian 9y ago
    Does the 4k monitor have multiple inputs? If it does, then connect both laptops to different input channels and switch inputs on the monitor as needed. Then presumably all you would need is a USB switch for keyboard and mouse input. I have often wondered why no one offers wireless keyboard/mouse combos with multiple USB fobs and a switch on the keyboard to change which fob it talks to.
    - arghwhat 9y ago
      https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GUS402/dp/B00BD8I2OY https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GU...
  - arghwhat 9y ago
    Do you really want to have two computers where only one is ever in use, when you could have just one for half the cost? Your setup is rather peculiar, and wastes a computer. It is usually done with dual-booting or virtualization, while multiple inputs (which I bet your screen has) or HDMI switch could handle it as well (although without handling keyboard/mouse). KVM's were designed for server environments, sold to server environments, and only take server environments into consideration where VGA+USB will remain the status quo for years to come. If you're really set on a KVM, take a 4k-capable standalone HDMI switch, a USB "switch" (https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GUS402/dp/B00Y3CTDAY?th=1 https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GU..., or a USB KVM), and an arduino to strap it together as a unit. Unless servers do away with VGA (hahah, no), I doubt you'll find a product for an affordable price that does what you want.
tootie 9y ago
Server room KVMs are still going strong. I used them pretty regularly for a small in-store server room.

by sdfjkl 9y ago

fraqed 9y ago

As well the use of KVMs by PC enthusiasts has most likely been replaced by virtual machines.

OliverJones 9y ago

Yes, no doubt that rack-based kvm stuff disappeared. It was awful: hard to rig, hard to use with confidence. (Confidence? "Wait, wait, am I talking to data2 or web4 or what?) KVM was a just-barely-competent solution to a hair-on-fire (=== must-solve-now) problem.

NameOpenSource 9y ago
"What ? this was the production server ?... woops"

gambiting 9y ago

The easiest solution is to just buy an HDMI switch(there's loads of them, even ones which work with 4K signal, and they don't disrupt DHCP) and a USB switch. Total solution should fit in about 40-50 dollars.

Jaruzel 9y ago
But, that's more than one button to push! /s Seriously though, I am a regular user of DVI and VGA KVMs, which have served me well over the years, but now as I migrate to HDMI or DisplayPort connectors and higher resolutions, I'm finding myself having to re-think how I hook everything together.
- petecox 9y ago
  My windows laptop has only VGA out, so I hook up a second monitor via displaylink (usb -> DVI). I tried plugging the cable into my KVM switch and it worked okay on the Windows 10 side but there was some hot-plugging kernel panic when switching to Linux (must file a bug report!) So perhaps the future of KVM switches doesn't need video connectors such as VGA/DVI/DP if USB-C -> HDMI (as smartphones are adopting) becomes universal.
megaman22 9y ago
Are there any that don't suck bogwater? We've tried a handful for our conference rooms, and they are all universally flaky, with signal dropping randomly all the time.
- gambiting 9y ago
  I found that HDMI switches lose signal because the output device doesn't provide enough power for the switch to leach off. I've had a few of Aukey switches: https://www.amazon.co.uk/Switcher-Output-Splitter-Control-Blu-Ray-Black/dp/B071RHDWVV/ref=sr_1_2?ie=UTF8&qid=1512049679&sr=8-2&keywords=aukey+hdmi+switch https://www.amazon.co.uk/Switcher-Output-Splitter-Control-Bl... And once you plug in a dedicated 5V power supply they are rock solid.

Fnoord 9y ago

Anecdotal, I still use a KVM, for a specific use case. My PC has 2 monitors. My 1st monitor is standard usage, but my 2nd monitor is also used by my partner's PC. If she wants to use her computer, she gets the 2nd monitor (and the speakers) but otherwise I got a 2nd monitor to use. Practically, it saves me from having to use another set of speakers (you would not use 2 sets of speakers at the same time and I usually use headphones) and it also saves me from having to have or use 3 monitors which takes up more space and costs more. My partner doesn't use her computer a lot. When she does, all the hardware is available for her. I use the 2nd monitor during development, gaming, watching movies, and RDP session. As per some comments, I don't see how a VM would replace this use-case but I do understand its niche. Still, it saves us space.

Jaruzel 9y ago
You are not alone in this. For years my Partner and I had separate machines on a KVM. It was only when our Daughter moved out and her desk became free in our study that we no longer needed this setup.
- copperx 9y ago
  You had a daughter with your business partner? I'm now curious about the story.
  - grzm 9y ago
    Partner can be used in lieu of spouse for an unmarried couple.
    - bfhd 9y ago
      Even for married couples!
      - grzm 9y ago
        Thanks for the pointer. I wasn't happy with my phrasing. I should have just referenced a dictionary. MW's sense d is what I intended to convey: > "a person with whom one shares an intimate relationship : one member of a couple" https://www.merriam-webster.com/dictionary/partner https://www.merriam-webster.com/dictionary/partner

Jaruzel 9y ago

> Cut a HDMI cable in half and splay it out, then try switching that to another display. See what happens. If you took an ancient (but still available to buy) 25-pin 'parallel port' 4-port switch box with a rotary dial: https://photography-909a.kxcdn.com/product-images/03292/600/03292a.jpg https://photography-909a.kxcdn.com/product-images/03292/600/... And wired up the HDMI of two machines to output ports 1 & 3[1]. Then wired up the HDMI to the display to the input port (so effectively using the switch 'backwards'). As you are just simulating unplugging and re-plugging in the HDMI cable from each machine, via the switch, then surely this would work? There would be a bit of delay after switching as the HDMI/HDCP handshake completes, but unless you are switching every few minutes it should be usable? If it does work, then you've got 6 pins in the switch left to play with which could be used to switch usb devices (via a downstream hub) I've not done this, but have thought about it for a while now. ---- [1] Not ports 1 & 2 as you want to ensure total electrical isolation between the devices during switching.

gm-conspiracy 9y ago
I think the real isssue is with HDCP. The output device "ensures" the display device is authorized via a key to output. So, you would need an intermediary device that would accept any incoming signal, while also having a legit handshake with the output device. So, as you switch "inputs", there is no additional authorization required, because the output device does not detect any changes.
- sitkack 9y ago
  I believe this is also the case. The only organizations that can get exemptions from the HDCP Alliance (DRM Cabal) for devices that effectively circumvent encryption are for high end broadcast gear. Nothing precludes making a 4k KVM. Infact, a mid range AV main unit could probably route 4k KVM. https://usa.yamaha.com/products/audio_visual/av_receivers_amps/rx-a770_u/specs.html#product-tabs https://usa.yamaha.com/products/audio_visual/av_receivers_am...
- aidenn0 9y ago
  It's absolutely not HDCP since a 4k HDMI splitter is much cheaper than a 4k KVM. My guess is that with KVMs disappearing from server racks, there isn't enough volume to get the prices we used to get.

ghaff 9y ago

I actually bought a 4-port USB/HDMI switch model fairly recently. It's really just a clutter and convenience thing. I have a few computers, including Raspberry Pis, that I just fiddle around with sometimes. While I could do things in different ways, it's just simple to have one monitor, keyboard, and mouse and plug the computers into the switch.

j_s 9y ago
Do you have time to link the specific product if it has been working well for you? I personally wouldn't even mind a referral link though most get downvoted, especially if they lack a disclaimer. Something that can reliably connect to random/miscellaneous projects would be really useful to me!
- ghaff 9y ago
  This is what I got: https://www.amazon.com/gp/product/B06XRDS1CG/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1 https://www.amazon.com/gp/product/B06XRDS1CG/ref=oh_aui_deta... It seems to work fine although I haven't used it a huge amount.
  - ztjio 9y ago
    This does not meet the requirements of a modern workstation by my or the original article's requirements. This is limited to 1080p. We're looking at 4k as a minimum.
    - Zekio 9y ago
      There do exist some 4K and even freesync capable switches with USB3, I only know of the Level1techs ones Single Monitor https://store.level1techs.com/products/kvm-switch-single-monitor-model https://store.level1techs.com/products/kvm-switch-single-mon... Dual Monitor https://store.level1techs.com/products/kvm-switch-dual-monitor-model https://store.level1techs.com/products/kvm-switch-dual-monit...

deleted 9y ago

[deleted]

arghwhat 9y ago

At work, we have at least the first 30 racks with good 'ol VGA KVM's (no IP) and tray monitor/keyboard/touchpad, despite at least half of the servers having IPMI. Ain't going anywhere anytime soon. And no, no one needs 4k where a KVM belongs (which is in a server room).

djsumdog 9y ago
I needed a 4k switch. I had a nice monitor and a Linux and Windows laptop. I used the Win laptop for gaming and the Linux machine for pretty much everything else. Everything I tried was garbage: http://penguindreams.org/blog/4k-uhd-kvm-switches-the-startech-sv231mdpu2-and-the-iogear-GCS62DP/ http://penguindreams.org/blog/4k-uhd-kvm-switches-the-starte... There are a few in the $500+ range I have not tried, but you are wrong, there are use cases for 4k switching. I mean, do you really want to have two 4k monitors next to each other when you could just have one for half the cost?
- fian 9y ago
  Does the 4k monitor have multiple inputs? If it does, then connect both laptops to different input channels and switch inputs on the monitor as needed. Then presumably all you would need is a USB switch for keyboard and mouse input. I have often wondered why no one offers wireless keyboard/mouse combos with multiple USB fobs and a switch on the keyboard to change which fob it talks to.
  - arghwhat 9y ago
    https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GUS402/dp/B00BD8I2OY https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GU...
- arghwhat 9y ago
  Do you really want to have two computers where only one is ever in use, when you could have just one for half the cost? Your setup is rather peculiar, and wastes a computer. It is usually done with dual-booting or virtualization, while multiple inputs (which I bet your screen has) or HDMI switch could handle it as well (although without handling keyboard/mouse). KVM's were designed for server environments, sold to server environments, and only take server environments into consideration where VGA+USB will remain the status quo for years to come. If you're really set on a KVM, take a 4k-capable standalone HDMI switch, a USB "switch" (https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GUS402/dp/B00Y3CTDAY?th=1 https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GU..., or a USB KVM), and an arduino to strap it together as a unit. Unless servers do away with VGA (hahah, no), I doubt you'll find a product for an affordable price that does what you want.

tootie 9y ago

Server room KVMs are still going strong. I used them pretty regularly for a small in-store server room.