What are Oracle RAC components

Physical Nodes or Hosts.Physical Interconnects and interconnect protocols.Cluster Manager Software and Cluster Ready Services.Oracle Instances and Cache Fusion.Shared Disk System.Clustered File System, Raw Devices, Automatic Storage Management.

What is difference between Oracle and Oracle RAC?

Oracle RAC allows multiple computers to run Oracle RDBMS software simultaneously while accessing a single database, thus providing clustering. In a non-RAC Oracle database, a single instance accesses a single database. … In an Oracle RAC environment, 2 or more instances concurrently access a single database.

What is Oracle RAC architecture?

RAC Architecture. Oracle Real Application clusters allows multiple instances to access a single database, the instances will be running on multiple nodes. In an standard Oracle configuration a database can only be mounted by one instance but in a RAC environment many instances can access a single database.

What is RAC setup in Oracle?

Oracle Real Application Clusters (RAC) allow customers to run a single Oracle Database across multiple servers in order to maximize availability and enable horizontal scalability, while accessing shared storage.

What are the components of Oracle Clusterware?

The Oracle Clusterware includes two important components: the voting disk and the Oracle Cluster Registry (OCR). The voting disk is a file that manages information about node membership and the OCR is a file that manages cluster and Oracle Real Application Clusters (Oracle RAC) database configuration information.

Is Oracle RAC free?

Get started with RAC Explore with $300 in free credits and always free instances of Autonomous Database.

What are the benefits of Oracle RAC?

Lower Overall Cost of Ownership.
Expanded Scalability.
High Availability.
Transparency.
Buffer Cache Management.
Row Locking.
Recovery Manager, Online Backups, and Archiving.

What processes are required in RAC?

ACMS : Atomic Controlfile to Memory Service (ACMS) …
GTX0-j : Global Transaction Process. …
LMON : Global Enqueue Service Monitor. …
LMD : Global Enqueue Service Daemon. …
LMS : Global Cache Service Process. …
LCK0 : Instance Enqueue Process.

What is OLR and OCR in RAC?

ORACLE LOCAL REGISTRY(OLR) contains node-specific information required by OHASD . … As OCRs files are present in ASM diskgroup, While starting the CRS, it wont be able to Access OCR file to find the cluster resource information. Because at this point ASM instance would also be down.

What is OCR in Oracle RAC?

The purpose of the Oracle Cluster Registry (OCR) is to hold cluster and database configuration information for RAC and Cluster Ready Services (CRS) such as the cluster node list, and cluster database instance to node mapping, and CRS application resource profiles.

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What is CSSD and Crsd in Oracle RAC?

The CSSD was responsible for cluster synchronization, cluster membership, and group membership; EVMD handled event messaging for the processes; and CRSD managed the resources. Resource management such as start, stop, and monitor was done using scripts and processes that came under the RACG label.

What is CRS Oracle RAC?

Oracle clusterware, also known as Cluster Ready Services (CRS), manages Oracle cluster-related functions including membership, group services, global resource management, and databases. CRS is required for every Oracle 11g RAC instance and is only applicable to Oracle 11g.

What is Clusterware in Oracle RAC?

A High Availability Cluster and the Foundation for Oracle RAC. Oracle Clusterware is a portable cluster software that allows clustering of independent servers so that they cooperate as a single system.

Does Oracle RAC improve performance?

Performance tuning for an Oracle Real Application Clusters (Oracle RAC) database is very similar to performance tuning for a single-instance database. Many of the tuning tasks that you perform on single-instance Oracle databases can also improve performance of your Oracle RAC database.

Is Oracle RAC necessary?

You must have Oracle RAC on shared storage. If you do not, then it will not function properly. Any issue that you have with the shared disk configuration will eventually cause the system to fail, which generates an incorrect shared disk configuration error report.

How can I learn Oracle RAC?

Create a VM and install the Oracle software.
Add several virtual hard drives to a VM.
Configure them to be ASM disks.
Practice adding and removing disks within ASM.
Define failure groups. …
Practice backup/recovery using ASM.
Practice disaster recovery using ASM.

What is Oracle SE1 and SE2?

Oracle Database Standard Edition 2 (SE2) is available starting with Oracle Database 12c Release 1 (12.1. 0.2). For 12.1. 0.1, Oracle Database Standard Edition One (SE1) and Oracle Database Standard Edition (SE) are available. Table 1-1 Feature Availability for Oracle Database Editions.

What does Oracle Enterprise Edition include?

Oracle Database Enterprise Edition Oracle Database Enterprise Edition provides the performance, availability, scalability, and security required for mission-critical applications such as high-volume online transaction processing (OLTP) applications, query-intensive data warehouses, and demanding Internet applications.

What is Oracle Diagnostics Pack?

Oracle Diagnostics Pack offers a comprehensive set of real time and automatic performance diagnostics and monitoring functionality built into the core database engine and Oracle Enterprise Manager. … Oracle Diagnostics Pack takes the guesswork out of performance diagnostics.

What is the difference between OCR and Voting disk?

The voting disk is a file that manages information about node membership, and the OCR is a file that manages the cluster and Real Application Clusters (RAC) database configuration information. The Oracle Clusterware installation process creates the voting disk and the OCR on a shared storage volume.

What is interconnect in Oracle RAC?

The interconnect serves as the communication path between the nodes in the cluster database. Each Oracle instance uses the interconnect for the messaging that synchronizes each instance’s use of shared resources. Oracle also uses the interconnect to transmit data blocks that the multiple instances share.

What is VIP in RAC Oracle?

A VIP is a Virtual IP address, and should be defined in DNS and not assigned to any host or interface. When you install GRID/ASM home, you’ll specify the VIP names that were assigned in DNS. When Oracle Clusterware starts up, it will assign a VIP to each node in the cluster.

What is GES and GCS in Oracle RAC?

Global Cache Service (GCS) and Global Enqueue Service (GES) GCS and GES (which are basically RAC processes) play the key role in implementing Cache Fusion. GCS ensures a single system image of the data even though the data is accessed by multiple instances.

What are the major RAC wait events?

The most common wait events related to this are gc cr request and gc buffer busy (note that in Oracle RAC 9i and earlier these wait events were known as “global cache cr request”and “global cache buffer busy” wait events).

What are RAC database background processes?

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.

What is Cache Fusion in Oracle RAC?

As the name suggests, CACHE FUSION is the amalgamation of cache from each node/instance participating in the RAC, but it is not any physically secured memory component which can be configured unlike the usual buffer cache (or other SGA components) which is local to each node/instance.

What is split brain in RAC?

Split Brain is often used to describe the scenario when two or more nodes in a cluster, lose connectivity with one another but then continue to operate independently of each other, including acquiring logical or physical resources, under the incorrect assumption that the other process(es) are no longer operational or …

How do I find my master node in RAC?

Grep occsd Log file. [oracle @ tadrac1]: /u1/app/../cssd >grep -i “master node” ocssd.log | tail -1. …
Grep crsd log file. [oracle @ tadrac1]: /u1/app/../crsd>grep MASTER crsd.log | tail -1.
Query V$GES_RESOURCE view.
ocrconfig -showbackup. The node that store OCR backups is the master node.

How do I start and stop my RAC database?

emctl stop dbconsole.
srvctl stop listener -n racnode1.
srvctl stop database -d RACDB.
srvctl stop asm -n racnode1 -f.
srvctl stop asm -n racnode2 -f.
srvctl stop nodeapps -n racnode1 -f.
crsctl stop crs.

What are the wait events in Oracle?

Buffer Busy Wait: …
Db File Sequential Read : …
Enq: TX – row lock contention : …
Enq: TM – index contention : …
Row Cache Lock Wait : …
Read by Other Session :

How do I check my CRS status?

Querying CRS Resource Status.
Starting Cluster Resources by Using the crsctl Command.
Stopping Cluster Resources by Using the crsctl Command.
Starting Database Instances by Using the srvctl Command.
Stopping Database Instances by Using the srvctl Command.