LMS—Global Cache Service Process
•LMD—Global Enqueue Service Daemon
•LMON—Global Enqueue Service Monitor
•LCK0—Instance Enqueue Process
To ensure that each Oracle RAC database instance obtains the block that it needs to satisfy a query or transaction, Oracle RAC instances use two processes, the Global Cache Service (GCS) and the Global Enqueue Service (GES). The GCS and GES maintain records of the statuses of each data file and each cached block using a Global Resource Directory (GRD). The GRD contents are distributed across all of the active instances.