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Keyboard Video Mouse (KVM) Switches
tyen writes "I have accumulated a bevy of computers, and need to ditch all the monitors/room heaters on them save one. A KVM switch is the ideal way to do this, except every brand I have encountered working at a client site faced reliability problems. Anyone out there using a KVM switch they are pleased with? "
If you're talking about home use, I think one of these would be fine. If I switch using the button on the front of the thing, it works fine. If I switch from the keyboard (scroll-lock, scroll-lock, #key), I sometimes have to hit num-lock or caps-lock a couple of times to get the keyboard leds back in sync. Given that most KVM switches seem to cost >300, and this cost ~160, I can live with that.
I've worked for a year or more using the Cybex Commander KVM units. (Sorry, don't have URL handy - CDW or someone has them.) They worked flawlessly during the time I was using them and I _never_ had problems with them. However, they do cost more than the others but if what you want is reliability (donning asbestos underwear) _sometimes_ a higher price is warranted.
:-)
Just MHO.
"Bah!" - Dogbert
What does scrolllock-scrolllock-0-2 mean/do? I am missing the reference.
On a related note, the last time I looked into these, I noticed that most of them would only work in limited video modes - VGA, SVGA, XVGA, etc. A big limitation for someone that likes very high refresh rates and varying resolutions. Do the current offerings still have problems like this? I've been improvising, but it becomes more difficult as time passes and machines accumulate.
Rather than put all of your computers on a toggle type device, why not instead network them? That way, you could detach all of their monitors and keyboards and stuff save one, which will be your main console. All it needs to be is a nice setup running X11, that way you can run programs and administer all of the systems from once central location while having the versitility of each system's terminal on the screen at the same time!
Of course the problem with this is that it only works if the system is Unix or VMS. But bringing all of them together and still having seperate terminals for your Windows machines is still a nice space saver.
The mouse thing is _not_ surprising. Sometimes several brands of mice, especially on notebooks, change modes from Micro$oft to Mouse Systems or something else. A friend of mine couldn't get his KVM brand kvm switch to work well with his Logitech wheel mouse under Win-Doze. I've heard that this sort of thing happens even if all computers are _exactly_ the same.
"Bah!" - Dogbert
Belkin is at the extreme low end of computer products and you would be well advised to stay away from them.
Now as for KVM switches- For high end use consider one of the nice BlackBox KVM switches or a high end Raritan KVM switch. Basically these use a special connector which will not disconnect and cause problems. They can also be powered by the systems if the power supply dies or disconnects.
For low-end use consider a PowerReach KVM switch from Compucable. An 8 port version is only about $325 and the cable sets are not expensive. It supports some of the features of the high end switches (Power from ps2 ports, on screen display) it comes in a rack mount configuration and is a very cool purple color. More importantly I have had no stability issues with these switches except when using it with my DEC Alphas (which are picky). You can search for powerreach or compucable at buy.com as they seem to have very good prices on this sort of thing. (Avoid datacom warehouse at all costs as they are a ripoff when it comes to most prices)
-sirket
If quality of display means a lot to you, remember that every time you add another link in the chain of monitor cables between the video card and the monitor, you loose image quality. This is a major problem for us graphic designers who have to work at ultra-high resolutions. This is also a major critique of products like the Creative DxR2 DVD decoder card, which requires a VGA passthrough.
This works fine as long as your network is running. I prefer to have a solution that works as long as the _hardware_ is running. I've gone through too times of wondering if "b" was working when it was "a" all along. ;-)
"Bah!" - Dogbert
Tomauri has some great products, some of which I have used with success. To start, get good cables for your monitor such as Tomauri's "high density coax-style monitor cables" ... SKU 5378, 5373 or 5375 for 6, 10 or 15' lengths (from Blue Diamond). Prices from ~ $15 each ... (maybe less if you know someone -- I can't give you the real cost price because of the regulations as a reseller).
The switch box I recommend most is the Masterview 4 way automatic file server switch box. It can set you back about $225 but the features are great: It has built in monitor/mouse/keyboard emulation (so the PC senses each as being connected even if they aren't) and uses keyboard hotkeys to switch between machines. Supports both PS/2 and AT keyboards. SKU: 3074.
PS, Tomauri SKUs can be ordered from most wholesalers like Merisel and Ingram as well. If you're talking to your local computer sales people, just tell them the Tomauri #'s and ask for a price. You could always get your own account by calling 1-877-4-TOMAURI
- Michael T. Babcock <homepage>
- Michael T. Babcock (Yes, I blog)
Adding data:
I have a Belkin Omniview 8-port, expandable to 16 units (128 ports). It works OK, notable gripes are: At any video mode I get vertical stripes on the display, which I suppose is due to crosstalk in the cable mess. Another gripe is that everything has to be powered down in order to plug anything else in (according to the manual).
Now, the first one, I can live with. Convenience outweighs a few stripes.
The second one is intolerable. We're running Linux, we DON'T shut down our computers. Ever. I suppose if we all were stuck with windoze, we would plug new things in in the daily downtime. 99.9% uptime leaves more than enough time to plug a new computer in every day =-]
A minor gripe is that in order to access the on-screen display for chosing your node you have to hit scroll-lock twice. Not all that bad, but sometimes it doesn't catch and you have a computer sitting there thinking scroll lock is on. I would like to be able to choose another key, like F12 or print screen (I never have used either).
Good points are that the cables are really cheap, like $6 for a KVM set through Buy.com, cascading uses parallel printer cables. It's easy to set up and comes with rackmount hardware, you can even get Macintosh adapters. It can be bought for under $350.
Features I'd like: 2 independent heads, USB support, HOT PLUGGABILITY, SNMP management.
Hope this helps,
Tony
No. I have a Cybex Commander here at home... because we replaced them all at work. Use a Belkin Omniview or Omniview Pro. The Cybex may be alright for your needs, but it requires proprietary cables (I have many, but again they were surplus from work and therefore free). If you reboot a machine, you must select it on the Cybex as soon as it posts. Otherwise it presents no video or mouse or keyboard to the motherboard and, depending on your computer, that computer may decide it has mono video or like in the case of my ADSL firewall machine no video at all and you WON'T get video out of it at all. Telnet only. Not a big prob but a real pisser if you don't have enough UPS's for all your machines and your power at home is as unreliable as Georgia Power is for me (2 to 5 3-second outages per month). The Belkins can be had pretty cheaply. As I said, that's what we use at work now (I love it) and a friend who's not as cheap as me sprung $100 for one at home and loves it.
Raritan and Rose Electronics are two other companies that are pretty good and get a lot of attention.
We've got a great switch at work. It's running 2 SCO unix systems (Yeah, I know), an NT server (even worse), and a Linux box. It seems to work great. I'll get the name/model and post it tommorrow.
--
A mind is a terrible thing to taste.
"A mind is a terrible thing to taste."
I have a 4-port LinkSys switch I picked up at Fry's 1-1/2 years ago for $180. Even at 1600x1200 blurring is minimal; the trick was to get high-quality video cables (remember that you're doubling the length of cable and number of connectors, so proper impedance and low capacitance are a must). Some of my systems have PS/2-style keyboard and mouse connectors, others have old-style 5-pin DIN/9-pin D-style connectors. It handles both just fine. The only problem I have is that hot-keys don't work. Since it sits right beside my monitor that isn't a problem. Not using hot-keys might explain why I've never had caps-lock/num-lock/scroll-lock problems folks are reporting for the Belkin's. Or maybe it just works. In any case, it's close to the best $180 I've spent.
Then I found vnc.
My house is already networked with 24 ports of switched 100Mbit goodness. vnc was the icing on the cake. Cross-platform. Arbitrary window geometries and color depths AND I could still see what was going on with my main machine(s). With the price of a 2-node 100Mbit ethernet kit hovering just over $100US, I don't know if I'd ever bother with KVM
Caveat: I've tried vnc with machines that quite a bit slower than anything I have (the slow ones were 24MB RAM P200s with generic NICs and video cards), on a 10Mbit LAN. I won't say the word painful. I will say that you should maybe keep a newsreader or something open while you wait.
Still there's a certain joy in being able to play xdoom from a Windows box. I can do that. It's cool.
-- I wanna decide who lives and who dies - Crow T. Robot, MST3K
After asking the guys at work (the Eudora software lab at Qualcomm has about 50 computers in it, and many KVM switches), I finally found the best switch: the 4 port MasterView Plus Switch from Aten.
It has an amazing resolution (1920 x 1440 @ 75Hz -- take a long look at the resolution/refresh rate of other switches), and drives my high-res monitor perfectly (the Belkin I borrowed from work forced me into 1280 x 1024, which is not why I paid US$1200 for my monitor; the display also seemed fuzzy, which sucked). It's a smart switch, meaning you can reboot a machine without having to switch to that machine (the keyboard/mouse are kept active, so the machine thinks it has what it needs). It does PS/2 and serial mice/keyboards, and the lights on front also tell you what machine you're using. Another very cool feature is that it will even keep the capslock/numlock/scroll lock status the same when you switch between machines.
And to top it all off it has the coolest accessory of any KVM switch ever: a stainless steel foot pedal switch. You'll really like this. If you are the type that uses keyboard shortcuts, you'll really impress your friends with the foot switch. Your hands never leave the keyboard. I've even got my Aten KVM switch tucked out of sight, and it doesn't bug me at all because I can hit the pedal when I need to switch. It's very cool.
Get the Aten, you'll like it a lot. It's fairly pricey (about US$250), but worth it.
-B
Ash and Hickory, straight-grained and true, make excellent bludgeons, dandy for the cudgeling of vegetarians.
I use a rare unknown unit made by Multitech. Its called the Multitech Multiarray switch. It is rack mountable (I love rack mount!). It comes out of the box ready for 9 ports, and 3 of them can be chained without stealing the 9 ports on each. Not only this... the actual connectors on the unit are 25 pin ports. So if you used good sheilded Male to female 25 pin "serial/parallel" cables you can extend out the distance between the switchbox and the devices. It does NOT have keyboard support for changing the port. and after about a year, I accidently broke the up/down toggle switch. So after about 8$ in radio shack parts, I have a 20' corded remote control.. with the up/down buttons on it. a 1/8th inch stereo jack in the back of the box, a 20' stereo headphone extension cable, project box and two nice square pushbuttons... We have it in the rack in the dining room. Works great for all the PCs in the racks... the unix machines we have tied to a portmaster.... I would definitly say for the buck its awesome. Of course the other day my roomate found a 4 port Belkin like box in a dumpster. It works fine. Just my luck. But I am still happy with my switch. The cables teh switch comes with are about 6' in length... and have PS/2 style keyboard connectors and 9 pin mouse connectors... so a handfull of PS/2 to AT adaptors might be in order. I coudln't find that many ports for that amount of money. I didn't really care about having the keyboard macro... hitting a long key sequence.. its easier to reach over and hit up or down. I like to roll thru them quick. It also uses a 7 segment LED display to show the port (0 thru 9.. 0 being passthru to the next switchbox). I would have posted this under its own heading... but I guess anon cowards can't post new topics. - Tele Monster / www.757.org
I control a network of 118 machines, mixed Linux, Solaris, QNX and all flavours of MicroSloth. I run ORL's VNC, which is GPL'd except for the QNX boxes which I use Phindows running under WINE for.
:v)
The great beauty of VNC is that you don't even need a graphics card in the PC, which more than pays for the network card that you do need.
Vik
How does this switch handle hi res modes? The problem with my current KVM is that the quality of the video in hi res modes is completely unbearable. I'm not sure whether its the switch itself, or the cabling, or both.
By "hi res" I mean 85Mhz pixel clock (62.5 hsync, 76 vsync). That gives me 1024x768. I can probably go higher with my video card and monitor, but my current KVM can't even handle that resolution cleanly.
--
I'll second the monitor resolution problem. It's great for use in servers, but for workstations at high resolutions, I experienced a flashing of the screen which was untolerable for more than 2 seconds.
I went for years with 2 or 3 monitors of various sizes and qualities because of the blurring and other artifacts I saw with switches. Things have changed over the last couple of years. The switches I saw at customers/employers didn't seem suited for much beyond VGA. That's not true, now.
Things have changed, thanks to high-bandwidth VLSI video switching chips. Even my (relatively) cheap LinkSys lets me put up three side-by-side 80x80 Xterms with room left over (at 1600x1200x75Hz). There is a very slight blurring compared to connecting the monitor cable directly to the computer, but I get the same amount of blur just adding the monitor extension cable without the switch. There are no stripes, bands, ghosts, or other artifacts (beyond what I see from the video card itself--I've yet to see perfection in PC-class video cards, and in fact can see plenty of differences between cards through the switch). From what I've seen, other switches of recent design do as well (though pricier ones get you on-screen display and other niceties).
If you are doing production graphics (and you've spent >$3000 on a calibrated monitor and >$500 on a pro-grade video card) you shouldn't be playing around with switches in any case. But otherwise I think you've exaggerated the difference a switch makes. Cables make a much bigger difference, in my experience.
Here is the situation:
I have two monitors, and two computers, and in 6 months will have two more;
What I want to do is to be able to (for the time being) have one monitor/keyboard/mouse set infront of me, and another two the side, and be able to swap which console connects to which computer easily.
It would be nice, but is not required, that I be able to have the two consoles connect to any two of n computers, and be able to set this in an intelligent fashion...
any ideas/products?
We are all in the gutter, but some of us are looking at the stars --Oscar Wilde
Grrr. my nick is "Forward the Light Brigade"...
I suspect that other switches in the same price category will work similarly well.
Make sure you get descent video cables. Cables that bundle video, keyboard, and mouse together are a big convenience.
I had a Belkin before and both its keyboard emulation and its video quality left a lot to be desired; I returned it to the dealer after a week.
For evaluation of the video, I recommend running in the highest bandwidth video mode your video card will support (say, 1600x1200 at a fast refresh rate). For evaluation of the keyboard switch, try power cycling machines in various combinations. Also, if it matters to you, try playing some FPS games and see whether the key sequences of the switch are a problem and whether it locks up under that kind of usage.
I got the omnicube right when It came out (paid $110 for it). Since one of my workstations is at 1600x1200x75hz it looked TERRIBLE (ie. I couldn't read the screen at all) when using some of the cheap monitor cables I had laying around. The solution? I went to www.ultraspec.com and forked over $35 for one of their "ultra" 2M cables and another $25 for one of their "premium" 1.8M cables for my server at 1152x864x75hz Yeah paying almost $40 for a monitor cable is a little ridiculous but let me tell ya....the difference even between the "premium" and "ultra" cable was huge! Using the ultra cable, I don't notice a difference from not having it....the shielding in this thing is amazing....well worth the $35 IMHO.
The fuzziness problem isn't with the KVM...I've found the omnicube to be pretty good at that actually. The problem is in the shielding in the cable...since now you basically double the distance the signal travels through (if you have a 2M cable from pc to kvm and a 2M from kvm to monitor). The longer the cable the fuzzier the screen. So the better shielding your cable has, the more you offset this effect.
Right now I have one machine at 1600x1200x75, 2 machines at 1152x864x75, and another at 1280x1024x75. And they all look great. The problem though, is when you try going up to 85hz...unless you're using the ultra cable, it'll look worse than 75hz. This might be a limitation of omnicube though. But 75hz is enough for me.
So if you're gonna use high resolutions, get the best cable you can find...I'm sure there are other places...like places that sell industrial computer equipment you may find cables that can withstanding environments with high EMI.
-dr0ne
You can just add a getty to your serial port. If you can't get to your machine over the net, just plug in an old dumb terminal or, my favorite, use PalmTelnet.
-- Don't Tase me, bro!