Oracle B32100-01 - Manual (Page 120)

Overview of High Availability Configurations
7-2 Oracle Application Server Installation Guide
passive node mounts the shared storage and runs the Oracle Application Server
instance.
The most common properties of an OracleAS Cold Failover Cluster configuration
include:
■
Shared storage
The Oracle home for the Oracle Application Server instance is typically installed
on storage that is shared by the nodes in the OracleAS Cold Failover Cluster
topology. The passive Oracle Application Server instance has access to the same
Oracle binaries, configuration files, and data as the active instance.
■
Virtual hostname
During OracleAS Infrastructure installation, you can specify a virtual hostname in
the Specify Virtual Hostname screen. This OracleAS Infrastructure virtual
hostname can be managed by a hardware cluster or a load balancer and is used by
the middle-tier and OracleAS Infrastructure components to access the OracleAS
Infrastructure. This is regardless of whether the OracleAS Infrastructure is in a
single node installation, in the OracleAS Cold Failover Cluster solution, or in the
OracleAS Clusters solution.
The virtual hostname is associated with a virtual IP. This is the name that gives the
Oracle Application Server middle tiers a single system view of the OracleAS
Infrastructure with the help of a hardware cluster or load balancer. This name-IP
entry must be added to the DNS that the site uses, so that the middle-tier nodes
can associate with the OracleAS Infrastructure without having to add this entry
into their local /etc/hosts (or equivalent) file. For example, if the two physical
hostnames of the hardware cluster are node1.mycompany.com and
node2.mycompany.com
, the single view of this cluster can be provided by the
name selfservice.mycompany.com. In the DNS, selfservice maps to the
virtual IP address of the OracleAS Infrastructure, which either floats between
node1
and node2 via a hardware cluster or maps to node1 and node2 by a load
balancer, all without the middle tier knowing which physical node is active and
actually servicing a particular request.
You cannot specify a virtual hostname during Oracle Application Server
middle-tier installation, but you can still use a virtual hostname via a hardware
cluster or load balancer by following the post-installation configuration steps for
cold failover cluster middle tiers.
■
Failover procedure
An active-passive configuration also includes a set of scripts and procedures to
detect failure of the active instance and to failover to the passive instance while
minimizing downtime.
The advantages of an OracleAS Cold Failover Cluster configuration include:
■
Increased availability
If the active instance fails for any reason or must be taken offline, an identically
configured passive instance is prepared to take over at any time.
■
Reduced operating costs
In an active-passive configuration only one set of processes is up and serving
requests. Management of the active instance is generally less than managing an
array of active instances.
See Also: Oracle Application Server High Availability Guide