When Failover Occured
Failover is a course of action that one system responds
to unexpected hardware failures of other systems.
Traditionally, failover works with mirror systems in which
every operation is performed on two duplicated systems: one
operating, one stand-by. When the operating server fails,
the stand-by server will be activated and take on the server
service. This stand-by server will not become active until
the operating server system is down and failover occurs.
XLink’s ClusterBalancer software extends this failover
scheme to clustering system. This clustering system is made
up with two Windows 2000 systems. One is designated as the
Primary system, and the other Secondary system. During
normal operation, both systems are active and share the
service load to speed up operation. No duplicate work is
done. Failover will take place when a system or service
failure is detected.
XLink’s ClusterBalancer software supports two levels of
failover: system level and service/application level.
Service/application failover is when one (or some)
of the load-balanced service or application stops
functioning on one of the clustered systems, all service
requests normally shared by the two clustered systems will
be now handled by service/application of the still working
system.
XLink’s ClusterBalancer software runs on each of the
clustered systems co-dependently. This co-dependency
requires matching services running on both clustered systems
for all load-balanced services. It is this matching service
requirement that guarantees the service/application level
failover.
System failover is the situation when one of the
clustered systems is down entirely and all service used to
be carried by it are now loaded on the still working system.
While failover will pick up the failing system’s
workload automatically, failback will automatically restore
the original settings when the failing system is up and
running again. This combined functionality of failover/failback
is an important fault-tolerance function of mission-critical
services that rely on constant accessibility.
XLink ISA ClusterBalancer supports both failover and
failback. |
