1. What is RAC?
RAC stands for Real Application cluster. It is a clustering solution from Oracle Corporation that ensures
high availability of databases by providing instance failover, media failover features.
2. What are Oracle Clusterware Components ?
OCR,VD,OLR
3. What are Oracle Clusterware/Daemon processes?
ocssd, crsd, evmd,cttsd, oprocd, racgmain, racgimon
4. What are the special background processes for RAC (or) what is difference in stand-alone database & RAC database background processes?
LMON,LMNS,LMD,LCKn,DIAG
5. How do I identify the OCR file location?
check /var/opt/oracle/ocr.loc or /etc/ocr.loc
# ocrcheck
6. How do I identify the voting disk location?
# crsctl query css votedisk
7. How to take backup of OCR file?
#ocrconfig -manualbackup
#ocrconfig -export file_name.dmp
#ocrdump -backupfile my_file
$cp -p -R /u01/app/crs/cdata /u02/crs_backup/ocrbackup/RAC1
8. How to check backup of OCR files?
#ocrconfig –showbackup
9. How to recover OCR file?
#ocrconfig -restore backup_file.ocr
#ocrconfig -import file_name.dmp
10. How to take backup of voting file?
crsctl backup css votedisk -- from 11g R2
11. Who will manage OCR files?
crsd will manage OCR
12. Who will manage VD file ?
cssd will manage VD
13. If there is some issue with virtual IP how will you troubleshoot it?How will you change virtual ip?
To change the VIP (virtual IP) on a RAC node, use the command
[oracle@testnode oracle]$ srvctl modify nodeapps -A new_address
14. How you check the services in RAC Node?
We can check the service or start the services with 'srvctl' command.load balanced/TAF service named RAC online.
[oracle@TEST_NODE1 ~]$ srvctl start service -d orcl -s RAC
[oracle@TEST_NODE1 ~]$ crsstat
15. What is RAC and how is it different from non RAC databases?
RAC stands for Real Application Cluster, you have n number of instances running in their own separate nodes and based on the shared storage. Cluster is the key component and is a collection of servers operations as one unit. RAC is the best solution for high performance and high availably. Non RAC databases has single point of failure in case of hardware failure or server crash.
16. What would be the possible performance impact in a cluster if a less powerful node (e.g. slower CPU’s) is added to the cluster?
All processing will show down to the CPU speed of the slowest server.
17. How do we know which database instances are part of a RAC cluster?
You can query the V$ACTIVE_INSTANCES view to determine the member instances of the RAC cluster.
18. What is the default memory allocation for ASM?
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.
19. How do you backup ASM Metadata?
You can use md_backup to restore the ASM diskgroup configuration in-case of ASM diskgroup storage loss.
20. What files can be stored in the ASM diskgroup?
In 11g the following files can be stored in ASM diskgroups.
* Datafiles
* Redo logfiles
* Spfiles
* Password file
* In 12c the files below can also new be stored in the ASM Diskgroup
21. What components of the Grid should I back up?
The backups should include OLR, OCR and ASM Metadata.
22. What is SCAN?
Single Client Access Name (SCAN) is s a new Oracle Real Application Clusters (RAC) 11g Release 2 feature that provides a single name for clients to access an Oracle Database running in a cluster. The benefit is clients using SCAN do not need to change if you add or remove nodes in the cluster.
23. Mention what is new feature in Oracle ASM 12c?
The new feature added in Oracle ASM 12c is Oracle Flex ASM. Its a new ASM deployment model which increases instance database availability and reduces the Oracle ASM related resource consumption.
24. Mention how Oracle Flex ASM works?
Oracle Flex ASM instance when fails on a particular node, then the Oracle Flex ASM instance is passed over to another node in the cluster.
25. Mention where does the Clusterware write when there is a network or storage issue?
When there is a network or storage issue the network ping failure is written in $CRS_HOME/log
26. Mention what is the difference between Instance recovery and Crash recovery?
A crash recovery takes place when an instance crashes in a single node database on startup. When the same recovery for an instance is performed in RAC environment by the surviving nodes then it is called Instance recovery
Thank You
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