2.4. Storage Topology and DM-Multipath

Blocks-based clusters still tend to be deployed on Fiber Channel (FCP), but other technologies, such as iSCSI and FCoE (FCP transport captured into, typically, 10GbE Ethernet) also exist and are supported Oracle technologies. Device-Mapper multipath is a RHEL service that provides multiple pathways to the shared storage array. The array is usually accessed through an FCP switch that contains partitioned zones to regulate the use of the array. It is recommended that the all the FCP ports from the servers be isolated into a zone with the access ports (or HCAs) on the storage array. Although many customers use large storage arrays and then sub-divide their use amongst many consumers in the datacenter, we would not recommend this for Oracle clusters. Production Oracle databases tend to place great demands on storage arrays, and sharing them will only complicate the deployment. And complication always means a reduction in reliability.

In the iSCSI case, bonded NICs can be used in lieu of DM-multipath, but should be a separate set of NICs that will be used for the Red Hat Cluster Suite heartbeat service, or Oracle RAC Clusterware services.