Oracle RAC Interview Questions and Answers
Q1. What is Oracle Real Application Clusters?
Ans: Oracle RAC allows you to cluster Oracle databases.Oracle RAC uses Oracle Clusterware for the infrastructure to bind multiple servers in order that they perform as a single gadget.Oracle Clusterware is a portable cluster management answer this is included with Oracle Database.
Q2. What are the document garage options furnished with the aid of Oracle Database for Oracle RAC?
Ans: The record garage options provided by using Oracle Database for Oracle RAC are,
Automatic Storage Management (ASM)
OCFS2 and Oracle Cluster File System (OCFS)
A community file gadget
Q3. What is a CFS?
Ans: A cluster File System (CFS) is a record system that may be accessed (read and write) with the aid of all members in a cluster on the same time. This implies that every one participants of a cluster have the identical view.
Q4. What is cache fusion?
Ans: In a RAC environment, it's miles the combining of statistics blocks, which might be shipped across the interconnect from far off database caches (SGA) to the local node, which will satisfy the necessities for a transaction (DML, Query of Data Dictionary).
Q5. What is cut up brain?
Ans: When database nodes in a cluster are not able to communicate with every different, they will maintain to system and regulate the facts blocks independently. If the
identical block is changed via more than one instance, synchronization/locking of the information blocks does now not take vicinity and blocks may be overwritten via others within the cluster. This state is known as split brain.
Q6. What strategies are to be had to preserve the time synchronized on all nodes within the cluster?
Ans: Either the Network Time Protocol(NTP) may be configured or in 11gr2, Cluster Time Synchronization Service (CTSS) can be used.
Q7. Where are the Clusterware documents stored on a RAC environment?
Ans: The Clusterware is established on every node (on an Oracle Home) and on the shared disks (the vote casting disks and the CSR report)
Q8. What command might you use to test the supply of the RAC system?
Ans: crs_stat -t -v (-t -v are non-obligatory)
Q9. What is the minimum quantity of times you need to have so as to create a RAC?
Ans: You can create a RAC with just one server.
Q10. Name particular RAC heritage tactics
Ans: RAC strategies are: LMON, LMDx, LMSn, LKCx and DIAG.
Q11. What documents components in RAC have to reside on shared storage?
Ans: Spfiles, ControlFiles, Datafiles and Redolog files must be created on shared storage.
Q12. Where does the Clusterware write while there may be a community or Storage missed heartbeat?
Ans: The network ping failure is written in $CRS_HOME/log
Q13. How do you discover what OCR backups are to be had?
Ans: The ocrconfig -showbackup may be run to find out the automatic and manually run backups.
Q14. What is the interconnect used for?
Ans: It is a non-public community that's used to ship statistics blocks from one example to another for cache fusion. The physical statistics blocks as well as data dictionary blocks are shared across this interconnect.
Q15. How do you determine what protocol is being used for Interconnect visitors?
Ans: One of the methods is to observe the database alert log for the term when the database was commenced up.
Q16. If your OCR is corrupted what options do must solve this?
Ans: You can use both the logical or the bodily OCR backup replica to repair the Repository.
Q17. What is hangcheck timer used for ?
Ans: The hangcheck timer tests frequently the health of the machine. If the gadget hangs or forestall the node will be restarted routinely.
There are 2 key parameters for this module:
hangcheck-tick: this parameter defines the time frame among tests of machine health. The default fee is 60 seconds; Oracle recommends putting it to 30seconds.
Hangcheck-margin: this defines the maximum dangle postpone that need to be tolerated earlier than hangcheck-timer resets the RAC node.
Q18. What is the distinction between Crash recuperation and Instance recuperation?
Ans: When an instance crashes in a single node database on startup a crash recovery takes area. In a RAC enviornment the identical recovery for an example is done by using the surviving nodes called Instance recovery.
Q19. How will we recognise which database times are a part of a RAC cluster?
Ans: You can query the V$ACTIVE_INSTANCES view to determine the member times of the RAC cluster.
Q20. What it the ASM POWER_LIMIT?
Ans: This is the parameter which controls the wide variety of Allocation devices the ASM instance will attempt to rebalance at any given time. In ASM variations less than eleven.2.Zero.Three the default cost is 11 however it has been changed to unlimited in later versions.
Q21. What is a rolling upgrade?
Ans: A patch is considered a rolling if it's far may be carried out to the cluster binaries without having to shutting down the database in a RAC surroundings. All nodes within the cluster are patched in a rolling manner, one after the other, with simplest the node that is being patched unavailable even as all different example open.
Q22. What is the default reminiscence allocation for ASM?
Ans: In 10g the default SGA length is 1G in 11g it's far set to 256M and in 12c ASM it is set lower back to 1G.
Q23. How do you discover what object has its blocks being shipped across the instance the most?
Ans: You can use the dba_hist_seg_stats.
Q24. What is a VIP in RAC use for?
Ans: The VIP is an exchange Virtual IP deal with 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 software that the node has long past down. Without VIP, the utility will look forward to TCP timeout and then discover that the consultation is now not live due to the failure.
Q25. What additives of the Grid need to I lower back up?
Ans: The backups ought to encompass OLR, OCR and ASM Metadata.
Q26. Is there an clean manner to verify the stock for all far off nodes
Ans: You can run the opatch lsinventory -all_nodes command from a single node to have a look at the stock information for all nodes inside the cluster.
Q27. How do you backup ASM Metadata?
Ans: You can use md_backup to repair the ASM diskgroup configuration in-case of ASM diskgroup storage loss.
Q28. What documents can be saved inside the ASM diskgroup?
Ans: In 11g the subsequent documents may be saved in ASM diskgroups.
In 12c the files under also can new be stored within the ASM Diskgroup
Q29. What is OCLUMON used for in a cluster environment?
Ans: The Cluster Health Monitor (CHM) shops working machine metrics within the CHM repository for all nodes in a RAC cluster. It shops information on CPU, reminiscence, procedure, network and other OS statistics, This facts can later be retrieved and used to troubleshoot and identify any cluster related problems. It is a default factor of the 11gr2 grid install. The records is stored inside the master repository and replicated to a standby repository on a distinctive node.
Q30. What would be the viable performance effect in a cluster if a much less effective node (e.G. Slower CPU’s) is added to the cluster?
Ans: All processing will show all the way down to the CPU pace of the slowest server.
Q31. What is the motive of OLR?
Ans: Oracle Local repository includes information that permits the cluster strategies to be started out up with the OCR being in the ASM storage ssytem. Since the ASM record gadget is unavailable till the Grid processes are started out up a local reproduction of the contents of the OCR is needed that is stored in the OLR.
Q32. What are a number of the RAC specific parameters?
Ans: Some of the RAC parameters are:
INSTANCE_TYPE (RDBMS or ASM)
Q33. What is the destiny of the Oracle Grid?
Ans: The Grid software is becoming increasingly capable of now not just helping HA for Oracle Databases however also different packages including Oracle’s packages. With 12c there are more features and capability built-in and it's far less complicated to deploy those pre-built solutions, available for not unusual Oracle packages.