Oracle RAC Specific Processes

The following are the additional processes spawned for supporting the multi-instance coordination:

LMON - The Global Enqueue Service Monitor (LMON) monitors the entire cluster to manage the global enqueues and the resources. LMON manages instance and process failures and the associated recovery for the Global Cache Service (GCS) and Global Enqueue Service (GES). In particular, LMON handles the part of recovery associated with global resources. LMON-provided services are also known as cluster group services (CGS)

LMDx - The Global Enqueue Service Daemon (LMD) is the lock agent process that manages enqueue manager service requests for Global Cache Service enqueues to control access to global enqueues and resources. The LMD process also handles deadlock detection and remote enqueue requests. Remote resource requests are the requests originating from another instance.

LMSx - The Global Cache Service Processes (LMSx) are the processes that handle remote Global Cache Service (GCS) messages. Real Application Clusters software provides for up to 10 Global Cache Service Processes. The number of LMSx varies depending on the amount of messaging traffic among nodes in the cluster.

The LMSx handles the acquisition interrupt and blocking interrupt requests from the remote instances for Global Cache Service resources. For cross-instance consistent read requests, the LMSx will create a consistent read version of the block and send it to the requesting instance. The LMSx also controls the flow of messages to remote instances.

LMSn - The LMSn processes handle the blocking interrupts from the remote instance for the Global Cache Service resources by:

* Managing the resource requests and cross-instance call operations for the shared resources.

* Building a list of invalid lock elements and validating the lock elements during recovery

* Handling the  global lock deadlock detection and Monitoring for the lock conversion timeouts

LCKx - This process manages the global enqueue requests and the cross-instance broadcast. Workload is automatically shared and balanced when there are multiple Global Cache Service Processes (LMSx).

DIAG ? The Diagnosability Daemon monitors the health of the instance and captures the data for instance process failures.

The following shows typical background processes of the RAC instance named NYDB1.

$ rac-1a:NYDB1:/app/home/oracle >ps -ef | grep ora_

$ rac-1a:NYDB1:/app/home/oracle >

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