Syed Saad Ali
Syed Saad Ali
Installation/Configurations10g
September 1, 2017
Oracle RAC Daemons and Processes
Installation/Configurations10gInstallation/Configurations11gInstallation/Configurations12cOracle Database Material
Oracle RAC Daemons and Processes
OPROCd |
Process Monitor | provides basic cluster integrity services |
EVMd |
Event Management | spawns a child process event logger and generates callouts |
OCSSd |
Cluster Synchronization Services | basic node membership, group services, basic locking |
CRSd |
Cluster Ready Services | resource monitoring, failover and node recovery |
LMSn |
Lock Manager Server process – GCS | this is the cache fusion part, it handles the consistent copies of blocks that are tranferred between instances. It receives requests from LMD to perform lock requests. I rools back any uncommitted transactions. There can be upto ten LMS processes running and can be started dynamically if demand requires it. they manage lock manager service requests for GCS resources and send them to a service queue to be handled by the LMSn process. It also handles global deadlock detection and monitors for lock conversion timeouts. |
LMON |
Lock Monitor Process – GES | this process manages the GES, it maintains consistency of GCS memory in case of process death. It is also responsible for cluster reconfiguration and locks reconfiguration (node joining or leaving), it checks for instance deaths and listens for local messaging. A detailed log file is created that tracks any reconfigurations that have happened. |
LMD |
Lock Manager Daemon – GES | this manages the enqueue manager service requests for the GCS. It also handles deadlock detention and remote resource requests from other instances. |
LCK0 |
Lock Process – GES | manages instance resource requests and cross-instance call operations for shared resources. It builds a list of invalid lock elements and validates lock elements during recovery. |
DIAG |
Diagnostic Daemon | This is a lightweight process, it uses the DIAG framework to monitor the healt of the cluster. It captures information for later diagnosis in the event of failures. It will perform any neccessary recovery if an operational hang is detected. |
September 1, 2017
RAC Useful Parameters
Installation/Configurations10gInstallation/Configurations11gInstallation/Configurations12cOracle Database Material
RAC Useful Parameters
| cluster_interconnects | specify a specific IP address to use for the inetrconnect |
| _gcs_fast_config | enables fast reconfiguration for gcs locks (true|false) |
| _lm_master_weight | controls which instance will hold or (re)master more resources than others |
| _gcs_resources | controls the number of resources an instance will master at a time |
| _lm_tickets | controls the number of message tickets |
| _lm_ticket_active_sendback | controls the number of message tickets (aggressive messaging) |
| _db_block_max_cr_dba | limits the number of CR copies per DBA on the buffer cache (see grd) |
| _fairness_threshold | used when too many CR requested arrive for a particular buffer and the block becomes disowned (see grd) |
| _gc_affinity_time | specifies interval minutes for reamstering |
| _gc_affinity_limit | defines the number of times a instance access the resource before remastering |
| _gc_affinity_minimum | defines the minimum number of times a instance access the resource before remastering |
| _lm_file_affinity | disables dynamic remastering for the objects belonging to those files |
| _lm_dynamic_remastering | enable or disable remastering |
| _gc_defer_time | define the time by which an instance deferred downgrading a lock (see Cache Fusion) |
| _lgwr_async_broadcast | change the SCN boardcast method (see troubleshooting) |
September 1, 2017
RAC Useful Views And Tables
Installation/Configurations10gInstallation/Configurations11gInstallation/Configurations12cOracle Database Material
RAC Useful Views And Tables
|
GCS and Cache Fusion Diagnostics |
|
| v$cache | contains information about every cached block in the buffer cache |
| v$cache_transfer | contains information from the block headers in SGA that have been pinged at least once |
| v$instance_cache_transfer | contains information about the transfer of cache blocks through the interconnect |
| v$cr_block_server | contains statistics about CR block transfer across the instances |
| v$current_block_server | contains statistics about current block transfer across the instances |
| v$gc_element | contains one-to-one information for each global cache resource used by the buffer cache |
|
GES diagnostics |
|
| v$lock | contains information about locks held within a database and outstanding requests for locks and latches |
| v$ges_blocking_enqueue | contains information about locks that are being blocked or blocking others and locks that are known to the lock manager |
| v$enqueue_statistics | contains details about enqueue statistics in the instance |
| v$resource_limits | display enqueue statistics |
| v$locked_object | contains information about DML locks acquired by different transactions in databases with their mode held |
| v$ges_statistics | contains miscellaneous statistics for GES |
| v$ges_enqueue | contains information about all locks known to the lock manager |
| v$ges_convert_local | contains information about all local GES operations |
| v$ges_convert_remote | contains information about all remote GES operations |
| v$ges_resource | contains information about all resources known to the lock manager |
| v$ges_misc | contains information about messaging traffic information |
| v$ges_traffic_controller | contains information about the message ticket usage |
|
Dynamic Resource Remastering |
|
| v$hvmaster_info | contains information about current and previous master instances of GES resources in relation to hash value ID of resource |
| v$gcshvmaster_info | the same as above but globally |
| v$gcspfmaster_info | conatins information about current and previous masters about GCS resources belonging to files mapped to a particular master, including the number of times the resource has remastered |
|
Cluster Interconnect |
|
| v$cluster_interconnects | contains information about interconnects that are being used for cluster communication |
| v$configured_interconnects | same as above but also contains interconnects that AC is aware off that are not being used |
|
Miscellanous |
|
| v$service | services running on an instance |
| x$kjmsdp | display LMS daemon statistics |
| x$kjmddp | display LMD daemon statistics |
September 1, 2017
RAC Acronyms in Used
APPS DBAInstallation/Configurations10gInstallation/Configurations11gInstallation/Configurations12cOracle Database Material
Real Application Cluster Acronyms
GCS |
Global Cache Services | in memory database containing current locks and awaiting locks, also known as PCM |
GES |
Global Enqueue Services | coordinates the requests of all global enqueues uses the GCS, also known as non-PCM |
GRD |
Global Resource Directory | all resources available to the cluster (formed and managed by GCS and GES), see GRDfor more details |
GRM |
Global Resource Manager | helps to coordinate and communicate the locks requests between Oracle processes |
GSD |
Global Services Daemon | runs on each node with one GSD process per node. The GSD coordinates with the cluster manager to receive requests from clients such as the DBCA, EM, and the SRVCTL utility to execute administrative job tasks such as instance startup or shutdown. The GSD is not an Oracle instance background process and is therefore not started with the Oracle instance |
PCM (IDLM) |
Parallel Cache Management | formly know as (integrated) Distributed Lock Manager, its another name for GCS |
Resource |
n/a | it is a identifiable entity it basically has a name or a reference, it can be a area in memory, a disk file or an abstract entity |
Resource (Global) |
n/a | a resource that can be accessed by all the nodes within the cluster examples would be the following
Data Buffer Cache Block Transaction Enqueue Database Data Structures |
LVB |
Lock Value Block | contains a small amount of data regarding the lock |
TRFC |
Traffic Controller | controls the DLM traffic between instances (messaging tickets) |