Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 04-08-2006 Installation Manual page 270

SPOF
Single Point of Failure: Component of a system whose failure impairs the function-
ing of the whole system.
Failover
Another similar system component automatically takes over the function of a failed
component.
Cold Standby
The alternative hardware is on cold standby. The failover must be performed
manually, so the failure will be clearly apparent.
Warm Standby
The backup system runs in the background, so the transfer can take place automat-
ically. The data on both systems is automatically synchronized. For the user, the
failover is like a very fast automatic service reboot. However, the current transaction
may be aborted because it was not possible to synchronize the data prior to failure.
Hot Standby
Both systems permanently run in parallel—data on both systems is one hundred
percent synchronized. Users will not be aware of any failures. This level cannot
usually be reached without making a corresponding modification to the client. To
run both systems completely synchronously, the connections to the client must be
mirrored one hundred percent. This normally requires clients that have connections
with two or more servers at the same time and that communicate with all of them.
A normal Web browser cannot do this.
Load Balancing
The distribution of load within a cluster of computers. Load balancing is used in
an LVS scenario (Linux virtual server), for example (see
Virtual Server"
STONITH
Shot the other node in the head: Special hardware and software that ensures that a
faulty node does not write-access distributed media within a cluster, threatening
data consistency in the entire cluster. This involves simply disconnecting the system
from the main power supply.
270 Installation and Administration
(page 275)).
Section 12.5.2, "Linux