Hi
Any know that about swap server or pc if 1 server down then it swap to second server. how they use technoloy? thankWhat do you already know?
The idea is not new. It is now considered dead.
The current thing is, I believe, a virtual server moved in a cluster of rank computers using mostly software one very, very high bandwidth LAN. Often a optical link.
Tandem desktop computers are pointless. If you are a VIP and your desktop goes down, you tell one of your subordinates to go to lunch. And you go to his desktop, log in with your account and RUN off of the enterprise system that has copy of everything you have.

No, that is NOT a joke.

What I am saying is with optical networking, redundant hardware is no longer needed in a company that already has more that about ten DESKTOPS. Seldom does every user need his desktop at the same time.

Would you like to rephrase the question as:
'How do I sync two desktop PCs s so one can take over if the other fails.'

EDIT: Reference:
Fiber Distributed Data Interface (FDDI)
Quote

How It Works
Fiber Distributed Data Interface (FDDI) is usually implemented as a dual token-passing ring WITHIN a ring topology (for campus networks) or star topology (within a building). The dual ring CONSISTS of a primary and secondary ring. The primary ring carries data. The counter-rotating secondary ring can carry data in the opposite direction, but is more commonly reserved as a backup in case the primary ring goes down. This provides FDDI with the degree of fault tolerance necessary for network backbones. In the event of a failure on the primary ring, FDDI automatically reconfigures itself to use the secondary ring as shown in the illustration. Faults can be located and repaired using a fault isolation technique called beaconing. However, the secondary ring can also be configured for carrying data, extending the maximum potential bandwidth to 200 MBPS.
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