Specifications

Active - Active Grouping
In an active/active group, all servers are active processors, but they also serve as the backup server
for resource hierarchies on other servers. In an active/standby group, the primary server is processing
and any one of the backup servers can be configured to stand by in case of a failure on the primary
server. The standby systems can be smaller, lower-performance systems, but they must have the
processing capability to assure resource availability should the primary server fail.
Your physical connections and access to the shared resources determine your grouping options. To
be grouped, servers must have communications and heartbeat paths installed and operational, and all
servers must have access to the disk resources through a shared SCSI or Fibre Channel interface.
For example, in the following diagram, there is only one grouping option for the resource AppA on
Server 1. Server 2 is the only other server in the configuration that has shared access to the AppA
database.
The resource AppB on Server 3, however, could be configured for a group including any one of the
other three servers, because the shared SCSI bus in this example provides all four servers in the
configuration access to the AppB database.
Active - Active Grouping
In an active/active pair configuration, all servers are active processors; they also serve as the backup
server for resource hierarchies on other servers.
For example, the configuration example below shows two active/active pairs of servers. Server 1 is
processing AppA, but also serves as the backup server for AppX running on Server 2. The reverse is
also true. Server 2 is processing AppX, but also serves as the backup server for AppA running on
Server 1. Servers 3 and 4 have the same type of active/active relationships.
Although the configurations on Servers 1 and 2 and the configurations on Servers 3 and 4 are similar,
there is a critical difference. For the AppA and AppX applications, Servers 1 and 2 are the only
servers available for grouping. They are the only servers that have access to the shared resources.
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