RAC Useful Parameters

cluster_interconnects	specify a specific IP address to use for the inetrconnect
_gcs_fast_config	enables fast reconfiguration for gcs locks (true|false)
_lm_master_weight	controls which instance will hold or (re)master more resources than others
_gcs_resources	controls the number of resources an instance will master at a time
_lm_tickets	controls the number of message tickets
_lm_ticket_active_sendback	controls the number of message tickets (aggressive messaging)
_db_block_max_cr_dba	limits the number of CR copies per DBA on the buffer cache (see grd)
_fairness_threshold	used when too many CR requested arrive for a particular buffer and the block becomes disowned (see grd)
_gc_affinity_time	specifies interval minutes for reamstering
_gc_affinity_limit	defines the number of times a instance access the resource before remastering
_gc_affinity_minimum	defines the minimum number of times a instance access the resource before remastering
_lm_file_affinity	disables dynamic remastering for the objects belonging to those files
_lm_dynamic_remastering	enable or disable remastering
_gc_defer_time	define the time by which an instance deferred downgrading a lock (see Cache Fusion)
_lgwr_async_broadcast	change the SCN boardcast method (see troubleshooting)