Oeacle10g RAC Background Processes

RAC:
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Cluster: - Interconnected nodes act as a Single Server

- A cluster consists of multiple interconnected servers that appears to end users and applications as if they are one single server

- Multiple instances on different nodes access database files in Shared Storage

- Instances communicate through private interconnect(s).

Benefits of RAC:
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High Availability :- If one node failure, other nodes in the cluster can continue to operate and availability of database

Scalability:- Multiple instances allows clustered database to scale

Manageability:- Multiple legacy database can be consolidated into a single RAC database reducing management complexity

Cost of ownership:- RAC can be deployed on industry standard,reducing cost of purchasing maintenance and support

RAC Background Process:
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These background processes are supporting the multi-instance coordination:

LMON: Global Enqueue Service Monitor
Monitor entire cluster to manage the global enqueues and resources
LMON provided services are also known as Cluster Group Services(CGS)

LMDx: Global Enqueue Service Daemon(LMD)
lock agent process that manages for Global Cache Service enqueues to control access to global enqueues and resources

LMSx: Global Chase Service Processes, Handled remote(GCS). Upto 10 GCS cluster software provides

LCKx: Lock Process, Manages the global enqueue requests and the cross-instance broadcast(workload automatically shared and balanced when there are multiple Global Cache Service Process(LMSx)

DIAG: Diagnosibility Daemon
Monitoring the health of the instance and capture the data for instance failure process