Eliminating Computer Room Clutter
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.
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