11th Systems Administration Conference (LISA '97)
Increased Server Availability and Flexibility through Failover Capability
Michael R. Barber
Michigan Technological University
As computing systems become increasingly mission-critical, a high
level of service availability is essential. In order to maintain
service availability, it is desirable to have the ability to migrate
services from one server to another while having this change remain
transparent to the client machines. Although commercial solutions
exist which provide automatic failover capability, they are often
costly and restrictive.
Manual failover capability is useful for
providing service availability in situations where there is a hardware
failure, or where a server must be taken down for extended
maintenance. The discussion in this document will explore what
primitives can be used to construct a failover-capable system, the
issues involved in any service migration, and some of the specific
details about doing migration of services such as NFS, sendmail, and
World Wide Web.
Although implementation-specific examples
provided assume a Sun Solaris 2.x operating environment, the use of a
logical volume manager, and ethernet connectivity, other flavors of
UNIX may also contain the necessary building blocks needed to build a
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