Compaq ProLiant 6500 Compaq Parallel Database Cluster Model PDC/05000 for Orac - Page 50

2-26 Compaq Parallel Database Cluster Model PDC/O5000 for Oracle8i and Windows 2000 Administrator Guide I/O Path Configurations for Redundant Fibre Channel Arbitrated Loops Overview of FC-AL SAN Topology Fibre Channel standards define a multi-layered architecture for moving data across the storage area network (SAN). This layered architecture can be implemented using the Fibre Channel Fabric or the Fibre Channel Arbitrated Loop (FC-AL) topology. The PDC/O5000 supports both topologies. Storage Hubs are used to create redundant FC-ALs with a total 100 MBps bandwidth divided among all Storage Hub ports. The functional bandwidth available to any one device on a Storage Hub port is determined by the total population on the segment and the level of activity of devices on other ports. The more devices used, the less bandwidth that is available for each port. Redundant Fibre Channel Arbitrated Loops A redundant FC-AL consists of the PDC/O5000 cluster hardware used to connect host adapters to a particular set of shared storage devices using Storage Hubs. Each redundant FC-AL consists of the following hardware: I From two to four host adapters in each node I From two to four Storage Hubs I MA8000/EMA12000 Storage Subsystems, each containing two dual-port HSG80 Array Controllers I Fibre Channel cables used to connect the host adapters to the Storage Hubs and the Storage Hubs to the array controllers I GBIC-SW modules installed in host adapters, Storage Hubs, and array controllers A redundant FC-AL consists of from two to four individual loops. The number of loops present is determined by the number of host adapters installed in the redundant FC-AL: two host adapters create two loops and four host adapters create four loops. Figure 2-11 shows a two-node PDC/O5000 with a redundant FC-AL that contains four loops, one for each host adapter.