How many monitors, keyboards, and mouse devices do you have spread around your computer rooms? Probably one set for each server, right? This configuration not only results in a lot of clutter that makes working around your machines difficult, but monitors require huge amounts of electricity and generate a lot of heat.
Keyboard/video/mouse (KVM) switches have been around for a long time, but not for Windows NT. The problem plaguing NT and preventing the use of older KVM switches is that if you take away the mouse in NT (particularly a PS/2-style mouse) for even a moment, you lose cursor control. You either have to reboot the system to regain cursor control or learn how to navigate using the keyboard. If NT doesn't see the mouse or the keyboard when it boots, it won't load the drivers and you won't be able to use either device. Therefore, many older KVM switches won't work with NT because hitting the button on the switch is the same as disconnecting the device.
Newer switches address this problem by providing a keep-alive signal to the computer's peripheral bus. As far as NT is concerned, regardless of what system you switch to, the peripherals are available.
The Windows NT Magazine Lab reviewed six KVM switches with features ranging from keyboard and software controls to hard switches. Different models offer varying levels of functionality (and several vendors offer multiple versions, depending on what you want), number and types of ports and systems supported, extensibility, and price.
Our tests included five 8-port switches and one 4-port switch, with a mix of AT-style, serial, and PS/2 connectors, and DB15 video ports (although several switches used proprietary connectors and cables). Most of the units we tested had 12-foot cable sets (we didn't include these in the prices we list here because some switches used longer cables and some used shorter cables).
How We Tested
We didn't run the KVM switches through every possible configuration with every kind of peripheral and system. Instead, we tested the switches for basic functionality with various configurations. We attached switches that supported various connections (e.g., PS/2 DIN8 and AT-style DIN5 connectors) to all available device types at the same time. For switches that didn't support various connections, we simply attached those device types that the switches supported.
We tested the KVM switches using primarily Intel-based workstations, although several of the RISC machines in our lab, such as Alphas with PS/2 connectors, had no difficulty with the tests. We did not test the switches on Sun Microsystems or Macintosh systems, but the trouble-free operations we experienced with the Intel systems indicated that the switches should work with these other systems, provided you use the proper cables.
The Big Picture
The Lab's overall experience testing these switches was positive, so much so that we would like to keep them all--each product made our lives easy. We were able to use these switches to keep more than 35 workstations up and running at the same time. Before we started using the switches, we had to spread out all these systems across the lab, each with its own monitor, keyboard, and mouse. Once we installed the switches, we were able to condense the systems onto just a few racks (no more running around the room to work on each system), eliminate a lot of excess heat from the room, and cut our electric bills.
When deciding which switch to buy, you need to consider what kind of systems you have, the types of systems you have, how far apart they are, and whether you need to control several computer rooms from one location. You also need to consider how you are configured and whether you have racks that need hot-key control.
Most of the switches we tested are extensible--you can connect several to control many more systems at once--and offer reliable operation. Which switch you select depends on your needs, but any one of them is well worth the investment.
8-Port PS/2 Server Switch
Network Technologies, Inc.'s (NTI) 8-Port PS/2 Server Switch offers straightforward functionality for system switching. NTI offers switches with both front-panel buttons and hot keys for selecting attached computers (PS/2-style or others using adapter cables), models that support up to 48 systems, and cable lengths of up to 500 feet.
We reviewed the 8-port model, and it worked without a flaw throughout our tests. The switch offers standard PS/2 and DB15 video connectors, so setting up the cabling was easy. The switch passed through the video signal without distortion, and we encountered only a few times when the mouse controlling the attached systems did not work properly during the boot cycle, because of either a driver failure or a bad connection.
The front-panel buttons on the 8-port switch serve several purposes. If you press one of these buttons quickly, you select that individual channel, and it's LED. If you press one of these buttons and hold it in for more than half a second, the switch enters one of three special operation modes (you need to press and hold the button several times to cycle through all three modes).
In the first mode (scan), the switch cycles through all channels at a predetermined interval that you set. In the second mode (one-to-many broadcast), you can send keyboard signals to all attached systems simultaneously. This mode is useful for rebooting and executing the same program on all computers. The NTI 8-Port PS/2 Server Switch is the only switch we reviewed that offered this functionality. In the last mode (command), you can enable keyboard control (hot keys) for the switch--you can also engage command mode by pressing Ctrl-Shift-8 or * on the number pad. In this mode, the i and d keys increment and decrement the channel number, the s key turns scanning on and off, the t key followed by a number sets the scan interval, the p key and a number select a specific port, and the b key enables broadcasting. (NTI warns against using broadcasting while a system is rebooting.)
NTI doesn't support cascading multiple switches, but if you buy the 48-port version, you can attach almost the same number of computers as if you were using several of the competing models. The only drawback to using the 8-Port PS/2 Server Switch is that it doesn't provide an onscreen display of the current channel selection. It does offer a remote-operation capability through a special port (with an optional remote selector), but even the remote selector doesn't offer an onscreen display to show you which system you are using. The 8-Port PS/2 Server Switch worked well for us, and it can serve as a basic, no-frills switch for eliminating clutter in any MIS department.
Whether you're searching for a reliable, basic KVM switch or one with advanced functions, such as extensibility and programmability, you'll want to take a look at Cybex Computer Products' AutoView Commander. We tested a small, rack-mountable AutoView Commander 8-port switch (a 4-port version is available) that supports various device types (PS/2-style keyboard and mouse, AT-style keyboard, and serial mouse). The switch we reviewed required proprietary cables between the switch and the attached systems (although Cybex offers another AutoView switch that uses standard PS/2 cables). The proprietary nature of the switch means that Cybex can use the same connector for all ports on the box, which makes the switch smaller and lets you mix and match the devices attached (i.e., some can be AT-style and some can be PS/2). However, this approach also means you must buy your cables from Cybex, which offers cable lengths of 6 feet, 8 feet, 15 feet, and 30 feet.
The AutoView Commander has programmable functions, such as autoscanning (automatically cycling through the attached systems at a time interval you set) and channel naming (up to 14 characters so that you don't have to remember which letter goes to which computer). For extensibility, you can cascade 8 additional AutoView Commanders in a star configuration, for a total of 64 switchable ports--enough to handle a pretty good sized data center.
One handy feature of the AutoView Commander is that it can stay functional after a power failure. It can draw power directly from the systems attached through the keyboard or mouse ports so that if the switch loses power, it can keep running and maintain signal integrity. During the power failure, you can't switch the AutoView Commander and it won't display anything, but it leaves the keep-alive signal going so that the systems don't think they've lost touch with their peripherals (you'll notice that the power status lights also remain lit).
AutoView Commander's best feature is that it lets you switch between the attached systems either by pushing the front-panel buttons or by using hot keys. Using the buttons can be cumbersome because you don't have a lot of room on the switch to add labels over the buttons to tell you which systems they go to--you have only a letter identifying the channel. To use the buttons, you either have to place the unit on your workstation table or get the RSP Commander (a remote switching module) to operate the switch from a distance.
A better option for controlling the switch is keyboard-only control (hands-free operation). Simply hit the Ctrl key twice within a second, and an onscreen menu pops up that lets you select a system from a list of channel letters using the arrow and Enter keys. Whether you use the front-panel buttons or the hot keys on the keyboard, an onscreen identifier that shows for about five seconds lets you know what system you are operating. An LED over the channel button also lights up when you select that channel.
The only problem the Lab experienced with the AutoView Commander was that one of its video ports slightly warped and skewed the image about an inch to the left on the monitor. Other than that one port, the video pass-through quality was fine, even at high resolutions. The switch worked flawlessly and never dropped a mouse connection. Switch time either using a button or the keyboard is a little slow (you notice a pause as the switch engages the next circuit), but this interruption is annoying only when you need to scan rapidly through many systems to monitor tasks. For the price, you get a lot of functionality, clean NT operation, and a reliable unit with the AutoView Commander.
Raritan Computer's MasterConsole MCP8 is one of the more versatile units we reviewed. We tested the 8-port version of the switch (2-port, 4-port, and 16-port units are also available). You can connect up to 64 computers, such as PCs, Macs, and Sun Microsystems' systems that use PS/2-style, AT-style, and serial devices (or Apple Data Bus--ADB), in any mix by cascading switches. You can locate computers up to 60 feet from the switch and add a second keyboard, monitor, and mouse 150 feet from the switch.
You can use MasterConsole's main up and down buttons or hot keys to select channels and perform other functions such as autoscan. The MasterConsole unit the Lab reviewed is not programmable like the Cybex and Apex units. For this functionality, you need to purchase the MasterView option ($150 when purchased with the MasterConsole switch or $345 when purchased separately), which provides features such as channel naming and onscreen control from pop-up menus.
To enable the hot keys, press the Scroll Lock key twice within a half a second. After you enter this mode, you can use the arrow keys to navigate between channels and banks (for controlling more than one MasterConsole) or enter a number and hit the Enter key to select a specific channel. The drawback to both approaches is that you don't know which system you are looking at unless you know the numbers (or bank letters) that refer to those systems. Again, you need the MasterView option to see an onscreen display and define channel names (this limitation is a tad bothersome in such a high-end unit).
MasterConsole lets you create a 64-system control center by daisy-chaining four 16-port units. With proprietary cabling (heavy-duty and double-shielded) that can reach 60 feet, other switching modules, and optional repeaters that can boost the signal, you can piece together a system that will control 1024 computers, 300 feet away.
Even so, we found the cabling somewhat difficult to deal with. Because the proprietary cables are so well shielded, they are bulky and stiff, which makes bundling the cabling to get it out of the way difficult. The cabling arrangement we received (we asked for the ability to have various connections) left us with a jumble of cables: The main cables that come from the switch are paired such that each cable connects two computers to the switch. One of the main cables pairs two PS/2 mouse connectors, each serving two computers, and another main cable pairs two video connectors and two PS/2 keyboard connectors to serve two computers. You can attach converters to connect AT-style keyboard, serial mouse, or ADB, depending on what you need.
We were surprised that the switch connectors and cables were split into pairs--four PS/2 mouse connectors, each serving two computers, and four video and PS/2 keyboard connectors, each serving two computers. Ultimately, this approach makes sense, because it lets Raritan make heavily shielded cabling to reach the great distances (60 feet) without repeaters. However, the connectors and cables were confusing to set up and made quite a mess behind the rack.
MasterConsole is available in either a 19" or 24" rack-mountable chassis, and you can get remote control units to extend your reach. With the appropriate options, you can have dual-access (to set up another control center), multiple monitors (a video splitter), and many-to-one sharing (up to four KVM stations can control one PC).
Operationally, we had no complaints with the MasterConsole. It worked with all the systems we tested and the video was clear, even at high resolutions. The switch never failed on boot-up or lost connections. With the autoscan and autoskip (skipping inactive channels during manual switching or autoscan) features, we believe that the MasterConsole would work great in any data center environment, although you should consider getting the MasterView unit for added ease-of-use.
Outlook 8-Port Concentrator EL-80DT
Of the switches the Lab tested, Apex PC Solutions' Outlook 8-Port Concentrator EL-80DT was the cleanest and easiest unit to use. We just plugged it in and it worked--no fuss or confusion with the cables.
The Outlook is a single rack-space unit, so it fits nicely into a rack of network hardware without taking up too much room (several server manufacturers equip their rack configurations with the Outlook). The switch operates completely hands free (no buttons). As a result, you don't need to place this unit within reach on your desk or computer table. In fact, you're limited only by the maximum KVM cable length (up to 50 feet between the switch and the computer, depending on which type you have) for where you can put it.
Outlook's hands-free design means you control the switch from the attached keyboard and mouse. Pressing the Print Screen key brings up an onscreen menu of options (overlayed on the computer's display) for selecting a system and programming the switch. Through a series of commands (which you select with the arrow and Enter keys), you set the system names that appear on screen to match the names of your servers and workstations. This way, you don't need to remember which number on the switch goes to which computer. You can also perform other administrative functions, such as scanning through the ports on a set frequency and displaying device settings. Pressing the Esc key backs you out of the menus and exits you from the firmware utility, returning control over the attached systems.
You can control up to 64 systems by using nine Outlook switches--one master, with each of the other eight plugged into its ports (each switch can be 50 feet away from the master, and the attached computers can be 50 feet away from the switch, for a total of 100 feet). You can switch between modules via the firmware commands. The Outlook is PS/2 based only--no AT-style or serial connectors--and has nine sets of ports: one concentrator for the KVM and eight sets for the actual systems. It supports RS/6000, Mac, serial mouse devices, and HP-9000 and Sun systems with inline adapters for computer rooms with more than PCs or PC servers.
We never once lost a connection to a keyboard or mouse when running our NT test systems from the Outlook. It switches quickly when you select another system to view, and it maintains video signal integrity without blurring or shifting the image on the display. PS/2-based Alpha and PowerPC systems won't have any trouble working with this switch. The best feature about the Outlook is that it uses standard cable types instead of a proprietary connector or cable on the switch that converts to the standard connectors on the systems.
One feature you won't find on the Outlook is one-to-many activity replication so that you can repeat one action to all attached systems (Apex will have announced plans to provide this functionality by publication time). In addition, one Outlook switch can't support more than eight systems without daisy-chaining units (no 16-port or 32-port versions).
Overall, we found the Outlook to be very worthwhile and easy to use. The cost for the unit (without the bundle of cables--although it does come with one keyboard, one mouse, and one video cable) may seem high, but what you save in hassle, clutter, heat, and electricity more than makes up for it.
Rose Electronics' ServeView SVE-8U switch had the most buttons and lights of all the switches in our test group. Rather than providing an onscreen display, the ServeView provides a 2-character * 20-character fluorescent display indicating status and mode (Rose Electronics offers other models that include an onscreen display instead of the built-in fluorescent display).
We tested an 8-port version of the ServeView, a versatile unit that provides support for PCs (PS/2 and AT-style), UNIX, Macintosh, and Sun Microsystems systems. You can daisy-chain switches to control up to 256 systems, but you have to use standard cable lengths of 5 feet, 10 feet, 20 feet, 35 feet, 50 feet, 75 feet, and 100 feet. (Rose uses a proprietary connector and wiring scheme, so you must use its cables--however, Rose will custom build longer cables on request--up to 200 feet.).
One feature that stands out on this switch over the other switches we tested is that you can upgrade the ServeView. A switch can start with 4 ports, and you can add 12 more ports in 4-port card increments.
You can manually control the ServeView using the buttons on the front panel or use hot keys to select systems (and even an RS232 port). We found the panel buttons on the ServeView cumbersome. You have to press the membrane switches fairly hard to engage them, and the buttons obviously require proximity to the switch.
A better option is to use the hot keys. Pressing the left Ctrl key puts the switch into command mode, so that you can select a specific channel (enter the number), turn to the next channel, begin autoscan (at programmable intervals), or reset the keyboard or mouse. The ServeView's built-in display tells you everything it's doing. The ServeView also has other nice features to help conserve and manage resources in your data center, such as flash ROM, automatic screen-blanking (useful if your monitor doesn't have its own power management), and memory for keyboard states (such as Num Lock, Caps Lock, and Scroll Lock).
During our tests, we experienced a few functional difficulties. The ServeView didn't always switch reliably between attached systems--it would periodically lose the mouse or not keep it present during system boot so that the driver didn't load. On the whole, however, the switch worked the way it was supposed to in our NT enterprise testbed. The ServeView wasn't the cheapest switch we reviewed, but features such as upgradeability should be fairly useful to anyone with a growing data center.
StarTech's StarView SV421 switch is a 4-port PC switch that offers several features and options worthy of consideration. First, it has ports for a PS/2 keyboard and mouse, an AT-style keyboard and serial mouse, and standard DB15 video. All these connections are standard, so you can use any kind of cables you want. You can mix and match devices to fit your needs, with a standard cable length of up to 30 feet, or 262 feet with extender options (powered repeaters). And with special brackets, you can install the StarView into a standard 19-inch rack.
You can cascade up to three levels of StarView SV421 switches, giving you control over 64 separate computers (DIP switch settings tell the StarViews which switch is the master and which are the slaves). By pressing Ctrl-Alt-Shift simultaneously, entering the channel number you want, and then hitting the Enter key, you can switch channels without taking your fingers off the keyboard. However, the method gets more complicated if you have multiple levels of cascaded switches (you have to enter a series of numbers representing the different units). Plus, you have no indication of which system you are actually accessing, because the StarView doesn't provide an onscreen display--only an audible beep lets you know that you've switched channels. You must be able to see the LEDs on the front panel of the switch to see where you are pointed.
The StarView has one selection button on the front panel and one status LED for each channel. In a cascade environment, this button will cycle through only the systems attached. To select a specific channel, you must use the hot keys.
We encountered some initial minor operational difficulties with the StarView (it lost the PS/2 mouse connection to one of the workstations, and fixing the problem took several reboots and a certain amount of fiddling with the cable). Since then, however, the switch has worked well. Video is clear at low and high resolutions, the StarView switches reliably between channels, and the standard cabling makes this switch easy to fit into a data center. StarView also offers an autoscan feature (you set the time interval with DIP switches) and channel stepping with the left and right Shift keys while you're in hot-key mode. The only major drawback we discovered was that the StarView switch provides no indication--other than the LED--of which channel you are using.
For a basic and easy-to-use KVM switch that doesn't cost much and still functions exactly the way it should in an NT environment, you can't go wrong with any of the StarView switches (StarTech offers 2-port, 6-port, 8-port, and 16-port versions, as well). In fact, the StarView 4-port switch costs the same as switches we've purchased in the past that don't work well with NT and have no hot-key support.