Specifications
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18 KVM -- So Many Computers So Little Space
We did not want to use another set of user I/O when we setup the
server. The solution was to use a KVM (keyboard, video, mouse)
switch. KVM’s have been used in server farms for years to allow
single point of control for multiple computers. We purchased a 4 port
Belkin Omni View SE KVM. Port 1 is the workstation port 2 the
server leaving 2 ports for future use.
Switching between computers is done via a button on the KVM or
with a hot key sequence. When changing computers the KVM reconnects the keyboard, mouse and monitor
to the selected computer. The KVM creates virtual devices for each computer. When the user switches to a
particular computer the KVM programs the devices so they match the configuration of the virtual device.
Video Performance Tip -- Workstations tend to use much higher resolution and faster refresh rate
then servers. This results in a very high video data rate. This is usually not a problem for the KVM
itself but requires high quality video cable. The video cable should use coax for each of the three
video signals. Coax preserves the high frequency component of the signal and minimized cross
talk between the three video signals. Failure to use high quality cable will result in poor video
quality.
Mouse compatibility Tip -- The KVM works by fooling each computer into thinking it is
connected to a keyboard, mouse and monitor. The KVM must memorize commands sent to each
device and reconfigure the device each time the user selects a different computer. Mice cause
problems because so many different enhancements exist. For compatibility PS/2 mice power up in
two-button mouse mode this enables mouse functionally even if the correct driver is not installed.
At power up the driver performs a knock sequence to determine if it is a mouse it knows. If the
mouse answers correctly the driver switches it to an enhanced mode. This causes problems for
KVMs. Unless the KVM has a priori knowledge about the mouse it will be unable to configure it
properly. Depending on specifics this results in either loss of mouse control or the mouse reverts
to default two-button mode.
Mouse Workaround tip -- Turns out the Belkin KVM does not support my favorite mouse, the
Logitech Wheel mouse. Switching between systems cause the mouse to revert to default mode,
use of the wheel and left thumb button is disabled. To get around this problem the desktop runs the
Logitech mouse driver and is connected to port 1 on the KVM. When the system boots everything
is fine. Port 1 is the default port so at power up the host can access these devices directly. The
KVM passes proprietary commands but it does not remember them. The server is connected to
port 2 it is running the default Windows mouse driver. Switching to the server resets the mouse to
Microsoft mouse mode. Use of the left thumb button is lost but otherwise the mouse functions
correctly. Switching back to the main system the mouse is once again reset this time as a default
IBM PS/2 two-button mouse. The mouse still works but neither the thumbwheel or thumb button
is functional. I put the mouse control panel on the tool tray. Forcing the driver to search for new
devices resets the mouse back to full functionality. Not very elegant but it solved the problem.
19 Backup – Oops Protection
One of the benefits of switching from a laptop to a desktop file server was much larger hard disk. This
enabled us to use online backup.
19.1 On Line Backup
The server has shares allocated for each person. Currently it is equipped with a 45GB drive, if we need
more space there is room for an additional drive. We chose Second Copy 2000 as the backup utility.
Second Copy allows setting up multiple profiles. Each profile can be run automatically or manually. The
backup copy can be either a direct copy of the data or it can be a compressed image.
Figure 26 KVM