Using Serviceguard Extension for RAC Version A.11.20 - (August 2011)

Figure 5 Four-Node RAC Cluster
In this type of configuration, each node runs a separate instance of RAC and may run one or more
high availability packages as well.
The figure shows a dual Ethernet configuration with all four nodes connected to a disk array (the
details of the connections depend on the type of disk array). In addition, each node has a mirrored
root disk (R and R). Nodes may have multiple connections to the same array using alternate links
(PV links) to take advantage of the array's use of RAID levels for data protection.
Point-to-Point Connections to Storage Devices
Some storage devices allow point-to-point connection to a large number of host nodes without
using a shared SCSI bus. An example is shown in Figure 6, a cluster consisting of eight nodes
with a FibreChannel interconnect. (Client connection is provided through Ethernet.) The nodes
access shared data on an HP StorageWorks EVA or XP series or EMC disk array configured with
16 I/O ports. Each node is connected to the array using two separate Fibre channels configured
with PV Links. Each channel is a dedicated bus—there is no daisy-chaining.
Larger Clusters 21