If you're looking for Oracle RAC Interview Questions for Experienced or Freshers, you are at the right place. There are a lot of opportunities from many reputed companies in the world. According to research, Oracle RAC has a market share of about 1.0%. So, You still have the opportunity to move ahead in your career in Oracle RAC Development. Mindmajix offers Advanced Oracle RAC Interview Questions 2021 that helps you in cracking your interview & acquire a dream career as an Oracle RAC Developer.
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|Single system image available||No single system image|
|Proprietary interoperability with VIA||No standards available|
|Single ownership||Multiple Ownerships|
|Discoverable membership services||Central Index and decentral information to discover|
|Moderate throughput||Either too high or too low throughput|
|Guarantees capacity||High capacity, varies sometimes|
|Most commodity computers||Commodity and High-end computers|
|Centralized user management||Distributed user management|
|Centralized resource management||Distributed resource management|
|Central allocation and scheduling||DecentraliDistributed allocation and scheduling|
In a RAC environment, it is the combining of data blocks, which are shipped across the interconnect from remote database caches (SGA) to the local node, in order to fulfill the requirements for a transaction (DML, Query of Data Dictionary).
|Explore Oracle RAC Tutorial for more information|
When database nodes in a cluster are unable to communicate with each other, they may continue to process and modify the data blocks independently. If the same block is modified by more than one instance, synchronization/locking of the data blocks does not take place and blocks may be overwritten by others in the cluster. This state is called split-brain.
When an instance crashes in a single node database on startup a crash recovery takes place. In a RAC environment, the same recovery for an instance is performed by the surviving nodes called Instance recovery.
It is a private network that is used to ship data blocks from one instance to another for cache fusion. The physical data blocks, as well as data dictionary blocks, are shared across this interconnect.
One of the ways is to look at the database alert log for the time period when the database was started up.
Either the Network Time Protocol(NTP) can be configured or in 11gr2, Cluster Time Synchronization Service (CTSS) can be used.
Spfiles, ControlFiles, Datafiles, and Redolog files should be created on shared storage.
The network ping failure is written in $CRS_HOME/log
The OCR config - shows backup can be run to find out the automatic and manually run backups.
You can use either the logical or the physical OCR backup copy to restore the Repository.
You can use the dba_hist_seg_stats.
The VIP is an alternate Virtual IP address assigned to each node in a cluster. During a node failure, the VIP of the failed node moves to the surviving node and relays to the application that the node has gone down. Without VIP, the application will wait for TCP timeout and then find out that the session is no longer live due to the failure.
You can query the V$ACTIVE_INSTANCES view to determine the member instances of the RAC cluster.
The Cluster Health Monitor (CHM) stores operating system metrics in the CHM repository for all nodes in a RAC cluster. It stores information on CPU, memory, process, network, and other OS data, This information can later be retrieved and used to troubleshoot and identify any cluster-related issues. It is a default component of the 11gr2 grid install. The data is stored in the master repository and replicated to a standby repository on a different node.
All processing will show down to the CPU speed of the slowest server.
Oracle Local repository contains information that allows the cluster processes to be started up with the OCR being in the ASM storage system. Since the ASM file system is unavailable until the Grid processes are started up a local copy of the contents of the OCR is required which is stored in the OLR.
In 10g the default SGA size is 1G in 11g it is set to 256M and in 12c ASM it is set back to 1G.
|Also, checkout Overview On Oracle RAC Resource Mastering|
You can use md_backup to restore the ASM disk group configuration in case of ASM disk group storage loss.
In 11g the following files can be stored in ASM disk groups.
In 12c the files below can also now be stored in the ASM Diskgroup
This is the parameter that controls the number of Allocation units the ASM instance will try to rebalance at any given time. In ASM versions less than 126.96.36.199 the default value is 11 however it has been changed to unlimited in later versions.
A patch is considered rolling if it is can be applied to the cluster binaries without having to shut down the database in a RAC environment. All nodes in the cluster are patched in a rolling manner, one by one, with only the node which is being patched unavailable while all other instances open.
Some of the RAC parameters are:
The Grid software is becoming more and more capable of not just supporting HA for Oracle Databases but also other applications including Oracle’s applications. With 12c there are more features and functionality built-in and it is easier to deploy these pre-built solutions, available for common Oracle applications.
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The backups should include OLR, OCR, and ASM Metadata.
You can run the OPATCH LSINVENTORY -ALL_NODES command from a single node to look at the inventory details for all nodes in the cluster.
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