HP Serviceguard Extension for RAC (SGeRAC) manual Point-to-Point Connections to Storage Devices

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