list some of the Background Processes specific to Oracle RAC database?
RAC database instance has common background processes and memory structure as of a single instance node. In addition, it has additional processes and memory structure that are dedicated for GCS processes, GES and GRD.
Below is some of the list of RAC background processes:
LMS (Lock Manager Server): The Lock Manager Server is a GCS process. The process transfers the data blocks between the RAC instances for cache fusion requests. And the number of LMS process are set on a parameter file called GCS_SERVER_PROCESSES on the initialization parameter file, init.ora.
LMON (Lock Monitor): it is responsible for managing of the Global Enqueue service and for reconfiguration of lock resources at the time an instance leaves or joins a cluster. Besides, it is also responsible for dynamic lock remastering.
LMD (Lock Monitor Daemon): It is the Global Enqueue service process and it manages the incoming remote lock requests from other instances in the cluster.
LCK (Lock Process): It manages non-cache fusion resource requests, such as row and library cache requests.
DIAG (Diagnostic Daemon): Handles all the diagnostic work in a RAC instance.
The Grid user owns the background process for the ASM instance and the oracle user owns the background process for the RAC database instance.