you can see the oracle background processes with this query

8/6/2019 You Can See the Oracle Background Processes With This Query

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You can see the Oracle background processes with this query:

select *

from v$session

where type ='BACKGROUND';

Here are some of the most important Oracle background processes:

ARCH - (Optional) Archive process writes filled redo logs to the archive log location(s). InRAC, the various ARCH processes can be utilized to ensure that copies of the archived redo logsfor each instance are available to the other instances in the RAC setup should they be needed for recovery.

CJQ - Job Queue Process (CJQ) - Used for the job scheduler. The job scheduler includes a main program (the coordinator) and slave programs that the coordinator executes. The parameter job_queue_processes controls how many parallel job scheduler jobs can be executed at one time.

CKPT - Checkpoint process writes checkpoint information to control files and data file headers.

CQJ0 - Job queue controller process wakes up periodically and checks the job log. If a job isdue, it spawns Jnnnn processes to handle jobs.

DBWR - Database Writer or Dirty Buffer Writer process is responsible for writing dirty buffersfrom the database block cache to the database data files. Generally, DBWR only writes blocks back to the data files on commit, or when the cache is full and space has to be made for more blocks. The possible multiple DBWR processes in RAC must be coordinated through the lockingand global cache processes to ensure efficient processing is accomplished.

FMON - The database communicates with the mapping libraries provided by storage vendorsthrough an external non-Oracle Database process that is spawned by a background process calledFMON. FMON is responsible for managing the mapping information. When you specify theFILE_MAPPING initialization parameter for mapping data files to physical devices on a storagesubsystem, then the FMON process is spawned.

LGWR - Log Writer process is responsible for writing the log buffers out to the redo logs. InRAC, each RAC instance has its own LGWR process that maintains that instance¶s thread of redo logs.

LMON - Lock Manager process

MMON - The Oracle 10g background process to collect statistics for the Automatic WorkloadRepository (AWR).

MMNL - This process performs frequent and lightweight manageability-related tasks, such assession history capture and metrics computation.



MMAN - is used for internal database tasks that manage the automatic shared memory. MMANserves as the SGA Memory Broker and coordinates the sizing of the memory components.

PMON - Process Monitor process recovers failed process resources. If MTS (also called SharedServer Architecture) is being utilized, PMON monitors and restarts any failed dispatcher or

server processes. In RAC, PMON¶s role as service registration agent is particularly important.

Pnnn - (Optional) Parallel Query Slaves are started and stopped as needed to participate in parallel query operations.

RBAL - This process coordinates rebalance activity for disk groups in an Automatic StorageManagement instance.

SMON - System Monitor process recovers after instance failure and monitors temporarysegments and extents. SMON in a non-failed instance can also perform failed instance recoveryfor other failed RAC instance.

WMON - The "wakeup" monitor process

Data Guard/Streams/replication Background processes

DMON - The Data Guard Broker process.

SNP - The snapshot process.

MRP - Managed recovery process - For Data Guard, the background process that appliesarchived redo log to the standby database.

ORBn - performs the actual rebalance data extent movements in an Automatic StorageManagement instance. There can be many of these at a time, called ORB0, ORB1, and so forth.

OSMB - is present in a database instance using an Automatic Storage Management disk group. Itcommunicates with the Automatic Storage Management instance.

RFS - Remote File Server process - In Data Guard, the remote file server process on the standbydatabase receives archived redo logs from the primary database.

QMN - Queue Monitor Process (QMNn) - Used to manage Oracle Streams Advanced Queuing.

Oracle Real Application Clusters (RAC) Background Processes



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

DIAG: Diagnosability Daemon ± Monitors the health of the instance and captures the data for

instance process failures.

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 ServiceProcesses (LMSx).

LMON - The Global Enqueue Service Monitor (LMON) monitors the entire cluster to managethe global enqueues and the resources. LMON manages instance and process failures and theassociated 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 managesenqueue manager service requests for Global Cache Service enqueues to control access to globalenqueues and resources. The LMD process also handles deadlock detection and remote enqueuerequests. Remote resource requests are the requests originating from another instance.

LMSx - The Global Cache Service Processes (LMSx) are the processes that handle remoteGlobal Cache Service (GCS) messages. Real Application Clusters software provides for up to 10Global 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 remoteinstances for Global Cache Service resources. For cross-instance consistent read requests, theLMSx 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.

The LMSn processes handle the blocking interrupts from the remote instance for the GlobalCache Service resources by:

y Managing the resource requests and cross-instance call operations for the sharedresources.

y Building a list of invalid lock elements and validating the lock elements duringrecovery.

y Handling the global lock deadlock detection and Monitoring for the lock

conversion timeouts



RAC Background Processes:

1. Lock Monitor Processes ( LMON)2. Lock Monitor Services (LMS)3. Lock Monitor Daemon Process ( LMD)

4. LCKn ( Lock Process)5. DIAG (Diagnostic Daemon)

1. Lock Monitor Processes ( LMON)

It Maintains GCS memory structures.Handles the abnormal termination of processes and instances.Reconfiguration of locks & resources when an instance joins or leaves the cluster are handled byLMON ( During reconfiguration LMON generate the trace files)It responsible for executing dynamic lock remastering every 10 mins ( Only in 10g R2 & later versions).

LMON Processes manages the global locks & resources.It monitors all instances in cluster, primary for dictionary cache locks,library cache locks &deadlocks on deadlock sensitive on enqueue & resources.LMON also provides cluster group services.Also called Global enqueue service monitor.

2. Lock Monitor Services (LMS)

LMS is most very active background processes.Consuming significant amount of CPU time. ( 10g R2 - ensure that LMS process does notencounter the CPU starvation).

Its primary job is to transport blocks across the nodes for cache-fusion requests.If there is a consistent-read request, the LMS process rolls back the block, makes a Consistent-Read image of the block and then ship this block across the HSI (High Speed Interconnect) to the process requesting from a remote node.LMS must also check constantly with the LMD background process (or our GES process) to getthe lock requests placed by the LMD process.Each node have 2 or more LMS processes.

GCS_SERVER_PROCESSES --> no of LMS processes specified in init. ora parameter.Above parameter value set based on number of cpu's ( MIN(CPU_COUNT/2,2))10gR2, single CPU instance,only one LMS processes started.Increasing the parameter value,if global cache activity is very high.Also called the GCS (Global Cache Services) processes.

Internal View: X$KJMSDP



3. Lock Monitor Daemon Process ( LMDn)

LMD process performs global lock deadlock detection.Also monitors for lock conversion timeouts.Also sometimes referred to as the GES (Global Enqueue Service) daemon since its job is to

manage the global enqueue and global resource access.LMD process also handles deadlock detection and remote enqueue requests.Remote resource requests are the requests originating from another instance.Internal View: X$KJMDDP4. LCKn ( Lock Process)Manages instance resource requests & cross instance calls for shared resources.During instance recovery,it builds a list of invalid lock elements and validates lock elements.5. DIAG (Diagnostic Daemon)Oracle 10g - this one new background processes ( New enhanced diagnosability framework).Regularly monitors the health of the instance.Also checks instance hangs & deadlocks.

It captures the vital diagnostics data for instance & process failures.

you can see the oracle background processes with this query

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