Oracle RAC Daemons and Processes

 

OPROCd	Process Monitor	provides basic cluster integrity services
EVMd	Event Management	spawns a child process event logger and generates callouts
OCSSd	Cluster Synchronization Services	basic node membership, group services, basic locking
CRSd	Cluster Ready Services	resource monitoring, failover and node recovery
LMSn	Lock Manager Server process – GCS	this is the cache fusion part, it handles the consistent copies of blocks that are tranferred between instances. It receives requests from LMD to perform lock requests. I rools back any uncommitted transactions. There can be upto ten LMS processes running and can be started dynamically if demand requires it. they manage lock manager service requests for GCS resources and send them to a service queue to be handled by the LMSn process. It also handles global deadlock detection and monitors for lock conversion timeouts.
LMON	Lock Monitor Process – GES	this process manages the GES, it maintains consistency of GCS memory in case of process death. It is also responsible for cluster reconfiguration and locks reconfiguration (node joining or leaving), it checks for instance deaths and listens for local messaging. A detailed log file is created that tracks any reconfigurations that have happened.
LMD	Lock Manager Daemon – GES	this manages the enqueue manager service requests for the GCS. It also handles deadlock detention and remote resource requests from other instances.
LCK0	Lock Process – GES	manages instance resource requests and cross-instance call operations for shared resources. It builds a list of invalid lock elements and validates lock elements during recovery.
DIAG	Diagnostic Daemon	This is a lightweight process, it uses the DIAG framework to monitor the healt of the cluster. It captures information for later diagnosis in the event of failures. It will perform any neccessary recovery if an operational hang is detected.