USB KVMs Compared

EconolineCrush writes "KVM switches have always been a great way to control multiple machines, and now they're coming with all sorts of cool USB peripheral sharing and audio switching functionality. The Tech Report has a compared a couple of the newest KVM switches from Belkin and IOGear that're worth a look if VNC just doesn't do it for you."

Comments

PS/2 KVM switches

[Jacer]

have lots of problems. I've had 3 at work, they all have had the same scenario, they'll drop my mouse, perform actions I didn't do, quit working and until I power cycle it. I find VNC or RDP to be much easier, the only machines I connect to are servers, home and work. If I want to play a game, I'll use my high end workstation, but for all server tasks, It's all about VNC/RDP it has a lot less issues.

Re:PS/2 KVM switches

[BJH]

I've got an IOGear 4-port PS/2 KVm switch at home, and I've *never* had any problems with losing the mouse/keyboard connection on it.

In fact, the only problem I've ever had with it is when my 6-year-old AlphaServer refused to recognise my keyboard when connected to the switch, but all the other hardware I've tried with it (including an Alpha Miata workstation) have worked fine.

Re:PS/2 KVM switches

[tenman]

We have over 100 KVM switches in our building. in 30 different labs. Some are for SUN, some HP, most for PCs, and none of them ever give us problems. However, while we are not using the top of the line matrix KVMs, we are not using the SOHO crap that the artical rates. Our switches are setup to handle more than one user, 2 or 4, and control 8 to 32 machines. I am looking for a cheep way to buy one of these monsters for my home. The cheapest 4 user by 16 port system I have found is $3999. All of the switches we have can handle 1600x1200, and allow for PS/2 | DINN | serial style keyboard/mouse connections. All of them have on screen display, however none of them have USB or sound support. If you as a reader are looking into KVM switches, but don't want the sound of humming boxes under your desk, check out the longview extenders from . You can put this bad boy 200ft away from your kvm switch, and still view your screen at 1600x1200. We play FPS'ers via these titans all the time, with no loss of res, or screen update speed.
Also, while VNC (slow screen updates), is by far the greatest free tool of it's kind I have ever seen, there are cases where you really really want to be at the console, and yet still keep your boxes in a controled environment.

Re:PS/2 KVM switches

[Wavicle]

I've been plagued by this problem as well. I have a Belkin Omni 4 port KVM that gets almost no use because the mouse problems are so severe. I don't know if our problems are identical, but:

I only have the mouse problems with optical mice. I haven't tested all optical mice, but all mine are those microsoft intellimouse jobs that are really USB mice with a USB->PS/2 converter. Every single one of them has issues with the KVM switch.

If I use an old straight PS/2 intellimouse with a ball, I have no problems what so ever.

Also, I can get the mouse back in Linux, but you may not like the method: If I do a ctrl-alt-backspace (the X windows reset), the mouse will come back but everything that was open will close (in fact I'll have to re-login).

This problem really displayed how weak KDE/Gnome was with non-mouse support (using keyboard only). At least back in 2.0. I ultimately gave up and installed Exceed on a windows machine. Now the KVM gets no use.

YMMV, Hope this helps.

USB? What about the UXGA?

[Quasar1999]

Forget USB, I want a KVM that doesn't make my video cards output look like crap on my LCD... Why don't the manufacturers care about video quality at 1600x1200??? Just because I want to run multiple machines from one keyboard / LCD, doesn't mean that I'm running at VGA resolutions...

Re:USB? What about the UXGA?

[Osty]

Forget USB, I want a KVM that doesn't make my video cards output look like crap on my LCD... Why don't the manufacturers care about video quality at 1600x1200??? Just because I want to run multiple machines from one keyboard / LCD, doesn't mean that I'm running at VGA resolutions...

Try buying a quality KVM? I don't know about on LCD monitors (I haven't found a good-sized UXGA monitor in a comfortable price range for me, yet), but my 2pt IOGear USB KVM does 1600x1200 just fine on my 19" monitor, and the Cybex I use at work (not USB, unfortunately) does just as well on the 21" I have at work. Sure, if you're using a 5 year old KVM, you're probably not going to get very good video (unless you paid a lot of money 5 years ago). These days, you got ripped off if your KVM can't handle that.

Then again, things may be different when outputting on an LCD monitor (and I haven't seen any DVI-capable KVMs yet, so you can't mux the digital signal anyway, for the hihger-end LCDs).

Re:USB? What about the UXGA?

[decaying]

Perhaps a read of the article is needed?

quote :

Even at 1600x1200x32 at 75Hz (the best my monitor can do), I didn't see any ghosting or degradation in video quality with the SOHO OmniView USB/Audio.

and

IOGear's VGA cable is thinner than the ones we had from Belkin, which gave me some initial reservations about video signal quality, but I couldn't discern any difference in signal quality at 1600x1200x32 at 75Hz.

Re:USB? What about the UXGA?

[Foresto]

I have a Linksys KVM100SK 2 port KVM. It doesn't do USB, but it carries 1600x1200 video at 75Hz rather nicely. It's also cheap, comes with well shielded cables, supports my logitech wheel mouse in both Windows and Linux (using MS drivers on the OS), and doesn't require external power.

Re:USB? What about the UXGA?

[Polo]

I've found lots of the problems aren't so much the KVM as the cables. I got a KVM that came with a full set of cables, but they ghosted. I also bought some cheap VGA cables and they did the same thing.

However, when I bought some heavier duty cables with the ferrite cores on them, all the problems went away. (FYI I bought them locally at Action Computer in Sunnyvale, CA and they weren't too expensive)

Check your cables.

IOgear rocks

[EvilStein]

I've got one of these hooked up betwen my old ass G3/233 (with Mac OS X 10.1.5 and a combo USB/Firewire card, which works great) and my XP box. Plug commonly used devices into the extra ports on the front, like my Epson printer and my Handspring Visor, and it's good to go. I haven't had one single problem with the unit so far, and there was even a $20 rebate, so it was under $100 too. :-)

Re:IOgear rocks

[pnatural]

I agree with your comments. I've had an IOGear model G-CS104U for almost 3 years now. Never had a problem with the KVM, and every device I've plugged into it has worked as expected.

Also, the nicest thing about the unit is the fact that it came with all the necessary cables: 4 monitor cables and 4 USB square-type cables. I've never had the need to purchase additional cables specifically for the KVM. If only all products gave you everything you need...

You can get better than KVM for little more money.

[wackybrit]

KVMs are good, and they certainly have a variety of specialized uses, but they're not versatile enough, in my opinion. For example, in situations where two computer might need to both be used at once. What do you do then?

I've been looking around for solutions to this problem, because I've been thinking of opening a cybercafe, and I found something called BeTwin.

BeTwin is like the inverse of a KVM switch. Instead of having one keyboard, monitor, and mouse control one of a bunch of machines.. it turns a single machine -into- the bunch of machines.

Licences are $80 a head, and you can have up to 5 people independently using a single Windows 2000/XP machine just by plugging 5 USB keyboards, 5 USB mice, and 5 graphics cards into a computer (5 USB speakers too, if you think the USB bandwidth will take it!).. absolutely ideal for cybercafes where processing requirements on each station are low.

I have decided to go with the Linux route, rather than pay these fees, but thought I'd share it anyway.

My experience

[Doodhwala]

I use KVM switches at work and wish I had one at home. The ones I use are fairly expensive (Blackbox... they make lots of server products) and still leave something to be desired. On high resolutions, it takes a couple of seconds to switch between machines and even after paying so much, you can make out that the image is a little blurred on a 21 inch LCD (from Dell). And most of them dont work too well with laptops.

That said and done, I have to add that they are indespensible. Its amazing how much time it saves especially with keyboard shortcuts (you press Control-Control to get to the KVM and then a letter for the computer you want to switch two). Plus its essential in server rooms where these boxes can be cascaded to 64 or 128 machines. Now if only the good ones were a little bit more affordable for the rest of us....

Re:You can get better than KVM for little more mon

[Osty]

KVMs are good, and they certainly have a variety of specialized uses, but they're not versatile enough, in my opinion. For example, in situations where two computer might need to both be used at once. What do you do then?

Buy another keyboard, mouse, and monitor. That's not a problem KVMs were designed to fix. Think instead about the server room full of machines. Now, what do you do if/when you actually have to access one of those directly (ie, from the console, not over the LAN) (don't focus on the wrong part here. There are reasons you may need to directly access the console, like say your NIC died, or you're in the process of installing the OS. The reason here doesn't matter, what matters is that there are reasons why you would need to access the console directly rather than via ssh or vnc or X or terminal server or whatever)? Wheel out the cart with the monitor and keyboard? Or just go sit down at the station where you already have the monitor, keyboard, and mouse setup, with all the machines connected to Cybex KVM switches (the heavy-duty server room KVM switches are quite a bit different than the 2-port or 4-port switches you'll use at your desktop)? With the latter option, you never have to dig around behind a machine for the cables, or try to get back there to plug in that monitor on the cart. Just hit the hotkey, pick the machine you need to access, and you're there at the console.

Value of audio switching....

[Perianwyr Stormcrow]

If you only have two or three machines that all need audio, it's probably a better idea to either buy a small mixer board (the slightly expensive or skill-required choice) or run them all through one another (the cheapass choice.) If you have two machines there's really no reason not to do this, unless you plan on turning one off occasionally while using the other- but if you're a KVM kinda guy chances are you leave the damn things on eternally. If they're close enough to one another and you don't use cables that are too long or loop around other things- one could use a 8 inch mini cable to connect a pair of towers sitting next to one another- you won't have any signal problems.

The clear choice seems the IOGear device- it comes with cables, has OSD, and does not hail from the nauseating Brushed Metal Plastic Alien Bubbles school of design.

PC Weasels are often better than KVM switches.

[perry]

KVM switches are okay if you're just trying to avoid having more than one monitor for a couple of boxes you sit in front of, but they suck for managing a lot of hosts in real production work. I find that using a PC Weasel and a terminal server works a lot better than a KVM switch for remote management of Unix boxes running on PC hardware. KVM switches are okay some of the time, but PC Weasels rock!

Re:PC Weasels are often better than KVM switches.

[Zapman]

As another poster said, you're solving a different problem. Remote manangement (aka a developer needs access to the box) is what PC Weasel is all about.

If you have more than 10 servers, are you planning on getting 10 monitors, 10 keyboards and 10 mice, one set for each server? It's a waste of money, it's a HUGE waste of space, and it can't be made to look professional.

A good KVM let's you throw 1 monitor and keyboard at a bunch of boxes. You don't NEED true console access often; however, when you need it, nothing else will suffice.

In a data center environment, you're going to need both remote management and KVM.

Re:PC Weasels are often better than KVM switches.

[perry]

I've bought lots of boards with "server BIOSes" in the past, and they have never done as well as a PC Weasel for the job.

1) The serial BIOSes often do not work very well. Often they have trouble letting you do remotely what you can do locally even though that is what they're supposed to do for you.
2) They don't provide remote reset or watchdog timers. People then resort to additional kludges like remotely controlled power strips, etc.

In general, the PC Weasel "Does It Right".

Re:PC Weasels are often better than KVM switches.

[perry]

That's the point. You DON'T need "true" console access with a monitor and keyboard if you have a PC Weasel. You say "when you need it, nothing else will suffice" but that's exactly the point -- with PC Weasels, you never need it, because the remote management is as good or better than what you can do locally. You NEVER need physical presense again unless what you want to do is replace bad hardware.

Re:PC Weasels are often better than KVM switches.

[Zapman]

I am a sysadmin in a medium sized, mixed hardware datacenter. You have no idea how often hardware blows out, bios'en need updating, Roms need flashing.....

All of which are below the OS level. With no os, you must have console (or remote console)

We have around 150-200 servers lying around. We're back there almost everyday with SOMETHING, be it an initial OS install, hardware failure, or routine maintance. A good KVM system gives you the win of "few monitors, many servers", and also provides remote access to the console for when you don't need to replace something (say, you need to debug a Sun at the eeprom level)

All of which fall into "when you need console access, nothing else will suffice".

Re:PC Weasels are often better than KVM switches.

[joshuac]

---snip
All of which are below the OS level. With no os, you must have console (or remote console)
---snip

this is exactly what the weasel is for...assuming some of your intel-based servers come from one of the big players, you have probably used the Compaq lights out boards, or the built-in capabilties in the newer generations of Dell servers (older Dell servers used an add-in card like Compaq).

Basically, that is what the Weasel does, only not tied down to any specific manufacturers equipment, and it will not work over an IP network like the lights-out board will (only via an async terminal server. As a nifty bonus, the weasel plugged into the machine also watches and report standard post scan codes, to help quickly narrow down what exactly is dead on your dead machine, if necessary.

---snip
A good KVM system gives you the win of "few monitors, many servers", and also provides remote access to the console for when you don't need to replace something (say, you need to debug a Sun at the eeprom level)

---snip

Why would you should you need a framebuffer card and KVM to do this? I am not a Sun guy, but isn't that what port A and a 1u terminal server is for?

Re:PC Weasels are often better than KVM switches.

[Zapman]

It depends on your enviornment. for money, I work in one where people (read: management) like to have a monitor and keyboard that can get to each and every box.

For fun, I do solaris for another datacenter that's really into serial consoles, with 16 servers per console server.

The nice thing about the high end KVM stuff, is you can get huge numbers of servers on one system, and at least the one at work (CCC) can send sun and pc views to either sun or pc monitor/keyboard sets.

The nice thing about serial console is that you can telnet (well, ssh) into the console, and get to all of them, even on a 2400baud modem.

The down side is that serial consoles don't scale for spit. Most serial concentrators deal with 16 or less ports per. The 'for fun' datacenter has to have 10 or 20 console servers, whereas at work, we have 1 switch (128 port, and you can cascade several together), and however many monitor stations we need for our usage pattern.

What about video quality over long distances?

[TheCodeFoundry]

I use an Avocent SwitchView DT KVM in my home server rack right now, but it still necessitates the need to be physically at the server rack. The server rack is in a climate controlled room downstairs, but my home office is upstairs.

Ideally, what I would like to do is put ALL my computers (including my development workstation) in a new rack downstairs, so that all I have on my desk is my monitor, keyboard, mouse and speakers. A perfectly quiet office would be so nice. The problem is, how do I run video from the downstairs rack to my office (easily a 40' run)?

Any suggestions?

Re:What about video quality over long distances?

[shepd]

>The problem is, how do I run video from the downstairs rack to my office (easily a 40' run)?

• Depending on your length of run, RG-6 or RG-11 cable (3x or 5x your run -- depends on how much you care about the sync signals, or if you're lucky enough to be using a Sync-On-Green monitor :-). RG-6 is for shorter runs. TV coax is probably not good enough.
• A crimping tool, if you don't have one already.
• VGA to BNC cable. (you can skip this step if you want to do it yourself).
• BNC connectors.
• Serial mice will require a good quality, low gauge extension cable. PS/2 mice I wouldn't bother with. USB will not extend past 15 ft due to design flaws.
• Hack yourself up a keyboard lengthener with your leftover cable (for the clock and data signals). Here's the pinout. Put together your long BNC VGA cable in whatever fashion suits you, making sure that the RGB signals and returns are going through their proper, separate, cables.
  
  There ya go, home-made long video non-sucky cables made easy. :-)
  

Re:What about video quality over long distances?

[ryanwright]

The problem is, how do I run video from the downstairs rack to my office (easily a 40' run)?

Computer 1 -> KVM switch
Computer 2 -> KVM switch
Computer 3 -> KVM switch
etc.

KVM switch output -> Cybex/Avocent Longview extender -> One, single cat-5 cable -> Your computer upstairs.

The Longview extends your keyboard, monitor, mouse, speakers, microphone and a COM port up to 500 feet over one cat-5 cable. They work very well and I can see no video loss whatsoever.

Re:What about video quality over long distances?

[cmowire]

For the exact same distance, BNC cable will give you higher quality than HD15 because it has much much much better isolation. No crosstalk between the various signals because they are all shielded nicely.

So you will be able to run cables much longer before they start to look bad. How much longer? Depends on your individual standards of quality and how long you are trying to make it go. But they did some phenominal cable runs at a lecture hall in my alma mater that did 1600x1200 pretty well with BNC.

Re:OpenSSH

[Sancho]

Yeah, but KVMs don't get trojan'd ;)

Seriously, there are times I just like the full-screen display on my BSD box, or even want to have a local X display. Then there are those times when you won't have sshd running or (god forbid) it actually crashes and you need a local terminal. Sure, if you have it set up you could go in through the serial port, but who wants to do that? :)

For the record...

[AlphaOne]

The article states:

Unfortunately, both of these switches require large, boxy power adapters, the kind that don't tend to fit well in most surge protectors. Ideally, I'd like to see power pulled directly from one of the connected computers, but I'd settle for a power connector that moves the box away from the plug itself.

Perhaps my version of the Belkin KVM switch is different from the one they reviewed, but mine requires no external power. It works exactly as they wished it would... using power from the systems themselves.

I have a Windows PC using PS/2 plugged into port 1, an Apple G4 using USB into port 2, and a Linux box using PS/2 in port 3. The keyboard and mouse are PS/2 and the Belkin box effortlessly translates between them.

The problems they mention with USB peripheral disconnect is likely because the reviewer has connected the USB peripherals to the keyboard. You have to think of the KVM as its own USB device and not a hub. It's a KVM switch not a KVM-CD Burner-Digital Camera switch.

I can't comment on the other switch they review, but I love my Belkin KVM switch and I'd recommend it, especially if you have a mixed installation as I do. It works great with very few problems.

Re:For the record...

[MCRocker]

Actually, most of the KVM's I've used have this as an unintended feature. It can cause real problems because there are several situations where the KVM can get messed up and you can't control any of the machines. The only recourse is a reset of the KVM, but pulling the plug doesn't do that because it gets residual power from the keyboard and mouse connections to the running machines!

The only safe solution is to physically unplug ALL of the machines from the KVM, then power it down, power it back up and then plug all the cables back in.

The only other choice is to shutdown all of the computers and then power cycle the KVM, but of course since you don't have control of the machines, they can't be shut down nicely (in most cases). This is really not a good solution.

If you're using a UPS, make sure the KVM is plugged into it too because if the KVM loses power, but any of the machines on th KVM don't then you could experience the problems I've just described.

Degradation of the video quality?

[Futurepower(R)]

Be careful!

All the units besides the IOView degrade the video quality, I understand from long conversations with sales people. The IOView, with a Hitachi Elite 751 19 inch monitor and a Matrox G-450 video card at 1600 x 1200 and 75 Hz, actually gives slightly better quality. Odd result, I know, but I'm testing the IOGear MiniView SE 4-port as I type this.

The Tech Report article about 4-port units says, "The other units lack explicit video signal enhancement features, but their quality was the same on both a 17" Trinitron and a 19" NEC AccuSync 95F. Note that this does not mention the video card or the resolution or the refresh rate, indicating that the reviewer was probably not thinking that these were critical. Also, many people are just not good at seeing degradation.

The IOGear MiniView SE 4-port has a VERY funky way of switching between computers. One way, to press a control key twice, is okay, but only goes to next computer in line. The other is amazingly foolish:

[alt]+[ctr]+[shift]+[1 or 2 or 3 or 4]+[Enter]

(See page 14 of the MiniView SE 4-port manual (NOTE: .PDF file)

According to Samantha Martinez of KVM Switches Online (Samantha@kvm-switches-online.com Phone: 303-604-0237 Fax: 303-604-0724), "The only manufacturers that hold that resolution at that refresh rate are Aten/IOGear and Avocent." (They don't sell the Belkin unit, apparently. Aten makes IOGear. You can buy Aten units directly, but they are a worse buy.)

Note that you get 2 4-foot cables and 2 6-foot cables with the MiniView, not 4 6-foot cables.

Re:Degradation of the video quality?

[Artifex]

The IOGear MiniView SE 4-port has a VERY funky way of switching between computers. One way, to press a control key twice, is okay, but only goes to next computer in line. The other is amazingly foolish:

[alt]+[ctr]+[shift]+[1 or 2 or 3 or 4]+[Enter]

Dude... I don't even think about the keys anymore... now you've messed me up =)

Seriously, though, I have a 4 port PS/2 IOGear, and I mastered that keyboard switch in the first hour of use. My only complaint with the box, in fact, is that since it's a funky design, unless I bolt it underneath the table or something, the cables end up all over the place. I sure wish all the ports were on one side, and that it had the lights and the manual switch on a front panel, so I could put it on top of my desk. As it is, it's just floating back there with my hub and router and dsl model, etc. Thank goodness it doesn't need a power brick!

Oh yah: I also noticed that my work laptop, which was a Gateway Solo 9300, would lose connectivity with the mouse sometimes if I switched away. However, that's got to be a hardware issue on the Gateway side, because all the other machines I've hooked up have been fine. Just a word of warning to anyone with that particular system...

Re:PS/2 vs. USB

[Ziviyr]

I think having USB keyboard/mouse eliminates a common no no of plugging keyboards and mice in while the system is on with a port that is not designed for hotplugging.

Conversely I don't have to shut down every time (not horribly common, but enough to bug me) I dis/re-connect my mouse.

I don't need dead ports on my motherboard. Oh, and thats two less specialized ports on the system.

Re:PS/2 vs. USB

[Kredal]

Actually, USB mice do take advantage of the extra bandwidth they're given. They send updates to the machine twice as often as the older style PS/2... this is a Good Thing(tm) when playing FPSs and such.

As for the keyboard... I dunno, you'd have to type pretty darn fast to notice a difference. (:

awful belkin usb switch

[Faceprint]

I just finished returning the Belkin switch they reviewed here. I found it to be unusable, because of some major shortcomings.

The first thing was that it didn't work with my keyboard (logitech wireless). The F7 key was useless when plugged into the KVM. This was relatively minor, and they promised a firmware upgrade to fix it. Also, for those that care (I'm not one of them) the "internet keys" don't work.

The other problem I had was also keyboard related. The KVM has a keyboard emulator, which sends keyboard events to the computer, after receiving them from whatever keyboard you have plugged in. If you hold down a key for 3 seconds, the keyboard emulator fakes a key release. So scrolling stops after 3 seconds, and if you're ctl-clicking to select stuff, and you take more than 3 seconds to do it, suddenly the ctl-key is no longer pressed down, and you select just one item. I got the impression that this wasn't going to be fixed in firmware, but rather in the next revision of the product.

Also, the response time was sluggish at best, typing felt like i was in an ssh session over a slow link. Oh, and keys stuck sometimes.

I was planning on getting the IO Gear one instead, as I am told it doesn't have the same shortcomings. Here's hoping.

IOGear with 'USB sniffing' is the best

[SensitiveMale]

IOGear makes the best KVM switches that I have ever used.

I have used switches by Belkin, IOGear, Cybex, and a few others and they aren't even close in quality.

Only the IOGear does not display any video ghosting. IOGear video is rock solid with no fuzziness.

I switched to USB after I saw that IOGear uses 'USB sniffing". This neat feature eliminates that 3 to 4 second delay that every other USB KVM has and makes the switch as responsive as a PS2 switch.

IOGear has top quality stuff but their cables are a bit expensive.

Belkin Caveats

[fasteddie203]

The scroll lock hotkey on the Belkin's can cause the console to get stuck in linux, sometimes you have to hit the button on the KVM to unfreeze it - which can be a pain if you plan on only using the hotkeys and have the KVM in a out reach spot on your desk.

The belkin SOHO series (which I am using now) don't seem to reset PS/2 mice as reliably as the older Omnicubes (which I also use). Although, you don't need AC power for the SOHO series (it will draw power from keyboard ports). I had to return two units (over the course of 1.5 years) that would change channels (with loud beeps) in the middle of the night randomly - even though the PCs were off and wouldn't stop until I unplugged every single cable (including monitor). Adding an AC adapter from a spare omnicube fixed that problem.

Belkin does have a 3 year warrenty on their KVMs though, which has proven helpful for me.

Re:Belkin Caveats

[Junta]

If the thing gets scroll-locked, does ctrl-q unfreeze it? I know its a general rule and you ought to try it next time it freezes if you didn't already know about ctrl-s and ctrl-q.

I don't have any KVM, but I would think ctrl-q would unfreeze it in lieux of scroll lock, it works in non-kvm situations.

Re:Belkin Caveats

[MCRocker]

Also if you're using a wheel mouse on Linux with IMWheel (IMPS/2), then the Belkin switches will mess up the mouse severely when you switch. Typically, once you switch back, the pointer will be stuck in the corner. Moving the mouse will move the pointer a short distance from the corner, randomly register button clicks and snap the mouse back to the corner! On Caldera Linux, it's the upper right hand corner and on Red Hat Linux, it's the lower left. In either case, it makes the machine practically unusable.

If you know your keyboard shortcuts, you can shut down X and restart it and everything will be fine. Naturally this isn't a good solution, but the other day, I discovered that if you simply switch to one of the virtual terminals (ctrl-shift-F1, or F2 through 6) and then switch back to X (ctrl-shift-F7 or 9 on some systems) then you can get back control of the mouse without having to shut down X.

The Belkin KVM also causes problems with OS/2, but it only loses scroll information, so it's not critical. You have to restart the Work Place Shell or reboot to get it working again.

These are fairly serious problems that make the Belkin KVM's effectively useless under certain configurations.

Re:PS/2 ports... WHY??

[taiwanjohn]

I've had noxious troubles with PS/2 KVMs as well. Tried two different ones (about US$150/ea) and they both did exactly what you describe. Dropping the mouse, sending random key-events to machines... lockups... just plain DANGEROUS. I switched back to an old mechanical one, which also drops the mouse, but at least doesn't crash my systems. (I also use VNC for most work, and only use the KVM when absolutely necessary... which ain't very often.)

My question is: WHY did everyone switch to PS/2 in the first place? The old RS-232(?) ports could be hot-swapped at will. What POSSIBLE benefit could there be in switching to a protocol that requires a reboot to "re-capture" the input device if the connection is lost?

I've been wondering about this for years, and never heard a satisfactory answer. Anyone know?

--jrd

Iogear Miniview (2-port) rocks

[ldom]

I use the Iogear Miniview (2-port, CS-102U) everyday to switch between my Mac and my PC (W2000 and RH7.2). It works great, didn't cost much compared to the 4-port versions and comes with good cables. The user manual could be written by Dilbert as there's only one button to press.

I can't see a difference in the video quality (but I can't remember how it was before either...).

Anyway, a great buy for SOHO. And I'm not working for them...

Not designed to work with LCD screens

[Tim Browse]

Don't believe the hype. The guy asking specifically mentioned LCD screens - and they tend to look like hell when you put them through a KVM, especially one of these low end KVM switches. The reviewer was using a CRT screen, unless I'm mistaken.

I tried the previous Belkin USB KVM. It sucked. Apart from failing to switch smoothly at all - the keyboard would constantly disappear on switching and then I'd have to actually move it to another port to get it to work - the video signal was terrible. I was running at 1024x768@70Hz. It was blurry as hell.

I contacted Belkin to tell them it was the least impressive product I'd ever bought, detailing my problems.

On the monitor front, they replied that the switch was not designed to be used with LCD screens, which was why the quality was so bad.

Seriously, when you're used to pin sharp LCD displays, putting them through a KVM and turning them into something that looks like a 6 year old CRT is not such a great idea.

Maybe Belkin have fixed this issue with the new one, but bear it in mind if you have an LCD screen.

I actually have two monitors and one kbd/mouse, and use a simple Belkin no-frills USB switch with the kbd/mouse. It works like a charm - mainly because I don't think it tries to be too clever.

Oh yes - the KVM also looked rubbish on my CRT monitor too - but I traced this to the 'official' Belkin VGA cables - they sucked too. Replacing them with other (not expensive) makes of VGA extension leads improved the video quality on the CRT enormously. This was trivially proved by just using the leads as extension leads, taking the switch out of the equation. When using the Belkin leads, video quality was crap. Again, maybe they've fixed that now - I don't know - but it's something else to be aware of.

Tim

Re:I have never really liked USB for certain thing

[mccalli]

My logic has always said, why use up 3 of my computer's 4 USB ports on something that I already have a plug for anyway. Why let the others go to waste?

No reason - in your case don't switch. But future PC designs probably won't have the PS/2 port, so if you're buying new keyboards and mice then it makes sense to buy USB variants.

At the moment, connectors are simply a mess. Just think of the number of different types on a typical, well-equipped PC:

• PS/2
• USB (sometimes split into 1.1 and 2.0)
• Firewire
• Serial
• Parallel
• RCA sockets
• MPU-401 compatible (gameport to most, MIDI port to me
• S/PDIF
• VGA
• RJ-45
• RJ-11 for modem

Don't now about DVI - does it take a different connected to VGA? If so, add DVI to that lot. Gives you eleven (twelve including DVI) different connecters excluding the power cable, and we haven't started on the internal mess yet.

On the whole, standardising on the smallest number of connectors possible is a good thing. I'd personally like to see USB die as well and everything go firewire (and no, I'm not on a Mac), but that's a pipe-dream that isn't going to happen.

Cheers,
Ian

Re:You can get better than KVM for little more mon

[nathanh]

KVMs are good, and they certainly have a variety of specialized uses, but they're not versatile enough, in my opinion. For example, in situations where two computer might need to both be used at once. What do you do then?

Simply buy an IP KVM which supports multiple simultaneous sessions.

Re:Support for New Apple LCD Monitors?

[phillymjs]

If an ADC KVM exists, it is probably hideously expensive. Doubly so if Belkin makes it. You're probably better off buying a high-quality, 3rd-party LCD display with a standard connector, and a normal USB KVM. That's what I'm going to be doing in a few weeks when my existing beige G3 is replaced in my KVM setup with whatever Apple announces in the very near future. I would like the one-cable convenience of the ADC display, but I need the KVM connectability more.

If you really insist on getting an Apple display and you have some cash to spare, get the ADC display, and buy a 3rd-party 17" LCD to use on the VGA port on the G4, and use that as the G4's secondary display and the primary for the other machines hooked up to the KVM.

~Philly

problems with games, some computers

[_|()|\|]

I've had an IOGear model G-CS104U for almost 3 years now. Never had a problem with the KVM, and every device I've plugged into it has worked as expected.

I have the same unit. Inclusion of cables, and a few favorable comments on USENET, won out over Belkin. We use BlackBox at work, but that's more than I want to spend at home.

The biggest problem I've had so far is that the keyboard isn't responsive enough for action games. I can type fine, but I can't play Max Payne. I'm still investigating this problem, as it could be the USB adapter I'm using on the PS/2 keyboard.

Two of the computers had no problem using the keyboard and mouse: an Intel 810E running Linux and an Alladin V running Windows and Linux. The third system, a VIA KT133A, is not as happy. Windows 98 did not recognize the keyboard or mouse. I had to connect a keyboard directly to dismiss the "mouse not detected" message and install drivers. I have yet to get Linux to recognize the keyboard or mouse on this system.

Re:problems with games, some computers

[pnatural]

I currently run FreeBSD 4.3, Win2K and Debian Woody machines on my KVM. The Win2K and Debian boxes have VIA chipsets and the FreeBSD machine is an old intel board.

None have given me trouble, and all find the keyboard and mouse combo (Linux after loading the USB drivers, of course). I play Q3 and related mods exclusively on the Win2K machine, again with nary a problem. I've got a MS Natural keyboard and a MS optical mouse.

I had to resort to a PS/2 keyboard during installation of most of operating systems, and I keep it around for booting, BIOS tweaks and whatnot. I fear the PS/2 keyboard will be a necessity for several years to come.

Re:Garbage

[tweek]

Bullshit.

Actually it's a PERFECT article. I've been comtemplating a KVM switch at home for a few months now. I almost bought the belkin soho set but balked at the price. The only usb device I need to share is my mouse. My linux box has a usb hub with my sidewinder and sandisk cf reader.

This article helped tremendously and I'm looking forward to reading the responses on other possible models to look at.

So in closing, fuck you for thinking your opinion is the only thing that matters. I'm not one to support slashdot for the same lame stories but this one was one of the better ones.

prick.

How can a switch box improve video quality ???

[tmark]

The IOView, with a Hitachi Elite 751 19 inch monitor and a Matrox G-450 video card at 1600 x 1200 and 75 Hz, actually gives slightly better quality.

OK, I know you qualified this as an 'odd' result, but can someone explain how this could possibly be true ? If you're plugging the computer into the switchbox, the signal the SWITCHBOX is getting is the same signal the monitor would be getting if you didn't use the switchbox. But you're running more cable between the switchbox and the monitor and you have a device in between, to boot.

So how is the switchbox able to increase the video quality without introducing its own noise ?

Why choose between KVM and VNC?

[tswinzig]

The KVM switch we use is hooked up to a companion product from the same company, which converts the video signal to a very decent VNC server. I can connect to this VNC server, and using keyboard shortcuts, see exactly what is on the screen for any of the servers in the farm. I can even reboot a server, and watch it go through POST, etc, even stop it and interact with the BIOS menu... all because of how VNC is setup.

Check out StarTech KVM products. I think you can use that VNC box with other companies' KVM's also...

Re:Garbage

[tweek]

I do apologize on the bad language part. I get so frustrated sometimes with people posting the same old "This isn't an article for slashdot". My point still stands though.

This article actually is generating some of the realworld insight that I was looking for before making my purchase. You can't get that with a magazine article. I wasn't so concerned with the article linked as I was with the responses of readers.

Again, apologies for the language. It didn't help my point and actually detracted from it.

Re:A KVM switch with a VNC server!!!

[eyepeepackets]

What you may want is a console server. Console servers work through via a network and serial ports; one machine is the control machine where you connect via network and the other machines are accessable via serial ports from that one machine.

Console servers are very nice for some situations where you need to control a number of servers remotely. Sun sells these as do other vendors (Avocent sells them I think.) Remember, they're different from KVMs in that you don't plug in keyboards, mice and monitors, usually just a serial port.

If you need X (GUI environment), using ssh over a switched subnet is the best performance I've found. Have a central machine running X, ssh to the other machines and export the display variable to your central machine. Easy to control a number of machines from one monitor, keyboard and mouse, especially if you're using a multi-screen window manager like WindowMaker and its kin: Just setup a virtual screen for each machine and you're ready to rock and roll.

KVM II (!(2*KVM))

[Wintermancer]

A lot of praise is being said about the IOGear USB KVM switches. I personally have a their 4 port MiniView. It's advertised as being "Linux compatable".

It's a classic case of when someone says YMMV, and you find out that sure enough, your mile is not == 5,280 feet.

For instance, with a stock RedHat 7.3 kernel (2.4.18-3 through .18-5), the usb kernel modules does not like it at all. (Mind you, the 2.4.19.rc-3 patch does have a kludge for the Aten/IOGear USB switch, but I haven't played with it yet, so again, YMMV).

Their advertised keyboard hot-switching doesn't apparently like the MS Internet Keyboard Pro, either. So, it's either manually reach over to the KVM and select the system you want, or curse at the folks at IOGear who are patently clueless.

Otherwise than that, works great on the standard Windows boxes and the Mac platform.

But, for now, it's pretty much SSH/X-windows forwarding to use that Linux box.

I agree about the cables.

[Futurepower(R)]

I agree about the cables. Why did IOGear put the keyboard and mouse cables in the front? What could they possibly have been thinking?

There are a lot of Chinese, who work for these Chinese companies, who own only a bicycle, two pairs of black pants, and three white shirts. They are not the sort to worry about convenience in a product they will never own. (I've spent time in Taiwan buying computer parts.)

Re:I agree about the cables.

[Artifex]

There are a lot of Chinese, who work for these Chinese companies, who own only a bicycle, two pairs of black pants, and three white shirts. They are not the sort to worry about convenience in a product they will never own. (I've spent time in Taiwan buying computer parts.)

Maybe so, but a cable sprawl like this implies a generosity of real estate, something I doubt many of those hard workers have. More probably, it was just the simplest design to get a single-layer PCB or something.

I can't believe it's for ease of use, because reliance on colored ports to distinguish between mouse and keyboard is no good when you're fumbling in the dark under the desk, and the status LEDs are useless when it's under there, too.

Still, I love its crazy fake space streamlining, and the cables are surprisingly good for being so thin.

I don't know.

[Futurepower(R)]

A friend pointed out that there must be something imperfect in the way the Matrox card outputs its signal. Also, the difference is very small (but unmistakeable). I did not try the IOGear with the latest Matrox cards (G-550). I was too busy at the time.

Noise is not an issue here. The signals are very high level.

Changing the model without changing the model #.

[Futurepower(R)]

I didn't try the Belkin because Samantha told me about this.

I agree about the Aten form facter. Amazing mistake.

There is an issue with IOGear changing the model without changing the model number, so make sure you get fresh stock. Order from a big supplier.

I second that

[Just Some Guy]

I have the same Belkin KVM, and have had about 8 months of trouble-free switching joy. I have a FreeBSD box (USB), Intel Linux (USB), and Intel Linux (PS/2) connected and switch between them freely and without glitches.

Personally, I liked that the Belkin did not come with cables. Although that sounds strange at first, I realized that the odds of Belkin supplying the exact cabling that would work in my installation (factors include length, connector types (USB vs. PS/2), quality) were nil.

I would, however, strongly suggest paying the extra bucks for high-quality video cables to connect boxes with graphics displays. I upgraded from a Rat Shack VGA extender cord to a Belkin Pro-series integrated cord, and the difference in picture quality at 1600x1200x85 is noticeably better. I'd almost gotten used to the slight ghosting, but the Belkin cable cured that completely. Feel free to stick the cheap cables on your servers' text displays, though.

Re:PS/2 ports... WHY??

[eschasi]

Simple answer:

It was cheap when cheap mattered, and it replaced a connection without changing the way it worked. And for the record, the old connections were not RS-232 ports, so the question is a bit off the mark. Yes, they had some RS-232 components, but they weren't full-featured.

If memory serves, IBM invented this cable format for the PS/2. (You do remember IBM had a computer called the PS/2, right?) This particular connector might have been adapted from something else (strong resemblance to a Mac kbd/mouse connector, as I recall), but the big public play was with the PS/2. It was smaller, cheaper, etc, than the AT keyboard connector, and therefore a win all around. IBM then quickly adapted it for use with their `standard' PCs, and everybody followed. (Again, this was back in the days when IBM did something and everybody followed.) It was (and is) signal-compatible with the old keyboard, and I've still got a few of those ATPS2 keyboard adapters around somewhere in the dungeon.

At the time the AT-style keyboard connector was put on PCs (early 1980s), nobody ever dreamed we'd be having roomfuls of these things all cabled up to a single monitor/keyboard/mouse. The computers were too expensive for a person to own more than one, and not powerful or reliable enough to put into racks and stacks to provide specialized services. The kind of switching talked about here just wasn't envisioned, and in fact, would have been considered insane. Putting more expense into the component so it could be hot-swapped (and making the appropriate O/S changes) was simply not worth doing.

But eventually technology catches up, and the marriage of USB with keyboard/mouse permits the right thing to happen. One could argue that you ought to simply be able to plug/unplug the keyboard from USB host to USB host, and in fact, you can do that with some of them. But that still doesn't solve your monitor connection problems, and last time I checked, SVGA didn't work over USB. So a single switch that moves 3 components simultaneously is a big win.

I looked over the article posted at the top, and am pretty impressed. USB KVM switches are a great idea, and after reading over the above articles, I want one. In fact, I want both of 'em, because each has some very cool features.

Hmmm... so I guess I'll wait until the next generation comes out, when each company adds features from the other. :-)

Wrong - darned salespeople!

[Just Some Guy]

All the units besides the IOView degrade the video quality, I understand from long conversations with sales people.

I'm using the reviewed Belkin KVM with a Samsung SyncMaster 900NF fed from a Geforce2 at 1600x1200 at 75hz. I'm using an integrated video+USB cable made by Belkin, and have no perceivable degradation whatsoever. I used to have slight ghosting with cheap cables, but now there's none at all.

If you're a picky graphics designer-type, then you may "see" artifacts that noone else in the world can pick up, but the setup is beautiful for regular people.

Re:PS/2 vs. USB

[xtermz]

USB just unnecessarily complicates things in my opinion.

Huh? How about backing up that statement... The only problem I see with USB is poor support under linux. Is that USB's fault? Nope. Why do I get the impression your main reason for disliking USB is the fact that it's mainly a "Windows Only" standard... ?

Re:PS/2 vs. USB

[Junta]

Well, for one, hot plug is not consistant on PS/2 ports, and it is on USB.

For mice, the extra bandwidth results in more frequent updates.

And finally, it could help reduce cable problems. I mean, for example with a KVM, only one cord needs to plug in for both mouse and keyboard if it could double as a USB hub.
*Anything* that could help a KVM reduce cable mess is very good.

Re:Larger applications

[perry]

As I said in a previous message, PC Weasels. You'll never need to be physically near the machine again. They're beautiful.

Spoofing is a must, was: IOGear w/ 'USB sniffing'

[rjniland]

95% of the USB KVMs on the market rely on USB's hot-attach-detach plug&pray. This results in disconnect-reconnect events being seen by each host, with a minimum of 3-5 seconds for bus re-enumeration on EVERY switch operation. If your switch is also a hub, or supports devices other than K/M ("peripheral sharing"), it is almost certainly a simple non-spoofing switch.

If you only switch occasionally, this might be ok. If you frequently switch (as between RISC workstation and PC), it's unacceptable.

4% of USB KVMs are actually just simple mechanical switches. They have all the same problems as above, plus, striclty speaking, they violate USB rules, and can have nastly malfunctions if they don't have correct precedence for power-on/off (as USB connectors do).

1% of USB switches, just now entering the market, have "spoofing", aka "sniffing", aka emulation of devices. A correctly implemented spoofing switch never lets any host see a disconnect. Designing this is far from trivial. USB is complex, and the varieties of keyboards and mice are effectively infinite if you're trying to chase them all for purposes of emulation.

In addition to the IOgear mentioned above, there is only one other spoofing switch that I'm aware of, and it isn't fully debugged yet.

In the meantime, I recommend:

• Use a quality USB(host) to PS/2(device) adaptor, such as the Y-Mouse USB (www.ymouse.com) on each USB host.
• Use a PS/2 switch.

Wait for this USB KVM situation to get sorted out. And it will need to soon, as PS/2 ports will be vanishing from new machines next year (and already have from many 64-bit platforms).

Re:A KVM switch with a VNC server!!!

[ryanwright]

DS Series KVM switches. KVM over IP. Yes, it's worthless for gaming, but totally answers your question. No, you can't use VNC, you have to use a specific app made by Avocent, but it's exactly what you're asking for.

Unfortunately, their DSView app only runs under Windows.

Re:Just one question

[tenman]

If you are serious, then you have to realize that another house doesn't quite fit the bill here. I'm talking about putting your machines in a closet of your house (with A/C and a dehumidfier) like a guest bedroom closet. Then you can run your KVM controler anywhere you want. I have mine running to several different rooms. If my daughter wants to play a CD based game, or I want to load some media, I DO have to get up and go to the box, but that is very rare, as I have most of my media on a network file system (including CDROM ISO's).
If you wanted to have a floppy/cdrom/etc, then you could place a small case with no fans. Your workstation would only hold a floppy, a cd or cd-rw, maybe some USB/Serial/LPT ports, or what ever you wanted, and boot it over the network. The power supply wouldn't heat up with out a fan because you wouldn't be running any hard drives from it, and your motherboard doesn't have to run a fast chip 486 DX w/o fan would do. This would allow you to have a super quite work env, and still have the benefit of "external media" next to your station.

I hope this answers your questions. If you are a troll, maybe someone else will benefit from this.

Re:Just one question

[Hektor_Troy]

It does answer it to some extent; I just said "another house" to emphesize the distance you can run that thing at, but I guess humor is trolling around here :-)

Obviously it's a bit drastic to place it in another house, but how far away from the host computer can you place something like a USB2.0 or FireWire device? 10 meters? 20?

_I_ honestly don't care about floppy, I just mentioned disks because maybe someone else would want to know.