128个，根据(Doc ID 220970.1)

RAC: Frequently Asked Questions (RAC FAQ)

Technically and since Oracle RAC 10g Release 2, 100 nodes are supported in one cluster. This includes running 100 database instances belonging to the same (production) database on this cluster, using the Oracle Database Enterprise Edition (EE) with the Oracle RAC option and Oracle Clusterware only (no third party / vendor cluster solution underneath).

When using a third party / vendor cluster software the following limits apply (subject to change without notice):
Solaris Cluster: 8
HP-UX Service Guard: 16
HP Tru64: 8
IBM AIX:
* 8 nodes for Physical Shared (CLVM) SSA disk
* 16 nodes for Physical Shared (CLVM) non-SSA disk
* 128 nodes for Virtual Shared Disk (VSD)
* 128 nodes for GPFS
* Subject to storage subsystem limitations
Veritas: 8-16 nodes (check w/ Veritas)