About Oracle RAC Background Processes

The GCS and GES processes, and the GRD collaborate to enable Cache Fusion. The Oracle RAC processes and their identifiers are as follows:

• ACMS: Atomic Controlfile to Memory Service (ACMS)

  In an Oracle RAC environment, the ACMS per-instance process is an agent that contributes to ensuring a distributed SGA memory update is either globally committed on success or globally aborted if a failure occurs.

• GTX0-j: Global Transaction Process

  The GTX0-j process provides transparent support for XA global transactions in an Oracle RAC environment. The database autotunes the number of these processes based on the workload of XA global transactions.

• LMON: Global Enqueue Service Monitor

  The LMON process monitors global enqueues and resources across the cluster and performs global enqueue recovery operations.

• LMD: Global Enqueue Service Daemon

  The LMD process manages incoming remote resource requests within each instance.

• LMS: Global Cache Service Process

  The LMS process maintains records of the data file statuses and each cached block by recording information in a Global Resource Directory (GRD). The LMS process also controls the flow of messages to remote instances and manages global data block access and transmits block images between the buffer caches of different instances. This processing is part of the Cache Fusion feature.

• LCK0: Instance Enqueue Process

  The LCK0 process manages non-Cache Fusion resource requests such as library and row cache requests.

• RMSn: Oracle RAC Management Processes (RMSn)

  The RMSn processes perform manageability tasks for Oracle RAC. Tasks accomplished by an RMSn process include creation of resources related to Oracle RAC when new instances are added to the clusters.

• RSMN: Remote Slave Monitor manages background slave process creation and communication on remote instances. These background slave processes perform tasks on behalf of a coordinating process running in another instance.