Multitech RF500S Manuale Utente Scaricare il pdf (Pagina 40)

This is a 4-port device. Currently port 1 is connected to a desktop and port 2 to the server. The other two

ports are for future expansion.

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 -- Servers normally run video at fairly low resolution and refresh rate.

Desktops on the other hand use much higher resolution and faster refresh rate to reduce flicker on

large displays. This results in very high video data rates. This is usually not a problem for the

KVM itself but requires high quality video cables. The video cable should use coax for each of the

three video signals. Use of coax preserves the high frequency component of the signal and

minimized cross talk between the three colors. Failure to use high quality cable results 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 causes the mouse to revert to default mode,

use of the wheel and left thumb button is disabled. To get around this problem the desktop is

connected to port 1 on the KVM. The Logitech driver is installed. When the system boots

everything is fine. 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 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 solves the problem.

18 Backup – Oops Protection

One of the benefits of switching from a laptop to a desktop file server was much larger hard disk. This

enables us to use online backup. Online backup is convenient but it is vulnerable to virus attack. If one of

the machines on the network is compromised the virus is able to explore the network for shares. If it finds

any it may be able to delete or modify files.

18.1 On Line Backup

The server has shares allocated for each person. Currently it is running with a 45GB drive so that is more

then adequate, if we need more space there is room for an additional drive. Online backup provides

redundancy for most hardware and software problems. It is unlikely that both copies of the data will be

damages by the same failure. Online backup is also fast; access speed is limited by the speed of the

network. This makes it convenient to backup massive amount of data.

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Multitech RF500S Manuale Utente Pagina 40

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