Planning Quad Redundancy Configurations - Compaq 112726-001 - ProLiant - 6500 Administrator's Manual

Planning Quad Redundancy Configurations

For the highest possible level of I/O path redundancy, you can configure your
cluster for quad redundancy. This configuration provides four host adapters in
each of at least four nodes and four Storage Hubs for each redundant FC-AL.
The recommended quad redundancy configuration includes these I/O path
components:
I
At least four cluster nodes
I
Four host adapters in each node
I
Four Storage Hubs in each redundant FC-AL
I
Two dual-port array controllers in each storage subsystem
I
Fibre Channel cables and GBIC-SW modules for the connections
between the nodes and the switches or hubs, and between the switches
or hubs and the storage subsystems
In a quad redundancy configuration, both ports on both array controllers in
each storage subsystem access the same storagesets. Thus, up to three of the
four paths between the controllers and the shared data can fail and the cluster
nodes can still access the shared data. In addition, quad redundancy provides
continued access to shared storage in the event of multiple component failures
in the I/O paths between the nodes and the array controllers. For example, up
to three host adapters in a node can fail, or up to three Storage Hubs can fail,
and the nodes can still access shared storage over an I/O path containing
functional components.
Figure 4-4 shows an example of a quad redundancy configuration in a
redundant FC-AL. In this example, the following connections are made:
I
Each of four host adapters in each node connects to the same-numbered
Storage Hub (host adapter 1 to Storage Hub #1, host adapter 2 to
Storage Hub #2, host adapter 3 to Storage Hub #3, host adapter 4 to
Storage Hub #4).
I
The two odd-numbered Storage Hubs connect to port 1 of the array
controllers. Storage Hub #1 connects to array controller A, port 1 in
each storage subsystem. Storage Hub #3 connects to array controller B,
port 1 in each storage subsystem.
Cluster Planning 4-13