Compaq ProLiant 6400R Compaq Parallel Database Cluster Model PDC/05000 for Ora - Page 85

Cluster Planning 4-11 Planning Cluster Configurations for Redundant Fibre Channel Arbitrated Loops A redundant Fibre Channel Arbitrated Loop (FC-AL) is two or more Storage Hubs installed between host adapters in cluster nodes and array controllers in the shared storage subsystems. Each redundant FC-AL in a PDC/O5000 provides I/O path connections between each cluster node and the two ports on both array controllers in each MA8000/EMA12000 Storage Subsystem. Thus, each node can issue I/O requests to every storageset in the storage subsystems contained in that redundant FC-AL. A redundant FC-AL increases a PDC/O5000 cluster's availability by providing redundant components along the I/O path between the cluster nodes and the storage subsystems. If a particular component fails, data communication can continue over an I/O path containing functional components. To achieve redundancy in Fibre Channel Arbitrated Loops, you can implement either a dual redundancy configuration or a quad redundancy configuration. Planning Dual Redundancy Configurations A dual redundancy configuration is the minimum allowable configuration that provides redundancy along the I/O paths between the cluster nodes and the storage subsystems. This configuration provides two of each component along the I/O paths. These components include: I At least two cluster nodes I Two host adapters in each node I Two Storage Hubs I Two dual-port array controllers in each storage subsystem I Cables and GBIC-SW modules for the connections between the host adapters and the Storage Hubs and between the Storage Hubs and the array controllers If a redundant component along one of the I/O paths fails, the cluster nodes continue to access shared storage through the path containing the surviving component.