Step 1 Use a new FC HBA driver. The fault persists.
Step 2 Uninstall the multipathing software and connect the servers to the S6800E by using a single path. The fault persists.
Step 3 Replace the Oracle version. The fault persists.
Step 4 Replace the operating system version. The fault persists.
Step 5 After analyses, the cause is that the two IBM X3950 servers employ stacking architecture. Split the two stacked enclosures into four independent servers and install four-node Oracle RAC. The fault is rectified.