Introduction to Oracle RAC Interview Questions and Answers
When you talk about computing related to database, Oracle RAC (Real Application Clusters) provides and support software related to high availability and clustering within the Oracle environments. By using Oracle RAC, a number of computers can access Relational Database Management System of Oracle at the same time even when they are using only a single database, thereby supporting clustering. The interconnect is used to connect multiple instances among themselves and they all work in perfect synchronization while trying to access the data. In this post, we are going to study some of the Oracle RAC Interview Questions.
Now, if you are looking for a job which is related to Oracle RAC then you need to prepare for the 2019 Oracle RAC Interview Questions. It is true that every interview is different as per the different job profiles. Here, we have prepared the important Oracle RAC Interview Questions and Answers which will help you get success in your interview.
In this 2019 Oracle RAC Interview Questions article, we shall present 10 most important and frequently used Oracle RAC interview questions. These questions are divided into two parts are as follows:
Part 1 – Oracle RAC Interview Questions (Basic)
This first part covers basic Oracle RAC Interview Questions and Answers
Q1. Explain split brain?
Answer:
It is related with the miscommunication among nodes of a cluster. Those database nodes then continue their processing and make relevant changes in their data blocks on their own. In case multiple instances are responsible for modifying one block, the data blocks are not able to synchronize among themselves and those writes will be done by others for the same block. This entire process is called the split brain.
Q2. Explain the use of VIP and OLR?
Answer:
The alternate to virtual IP address is called VIP. Every node of the cluster is mapped with VIP and therefore in case of any node failure the VIP notifies the application about the node being down and itself switches towards the surviving node. In the absence of VIP, the TCP timeout would be encountered by the application. This TCP timeout then would notify a dead session as a result of the failure.
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OLR or popularly known as Oracle Local Repository consists of details related to cluster and the processes related to it when the OCR is in the ASM system. The grid process takes time to start and in the meanwhile ASM system will also be unavailable and therefore an OCR local copy is booted which is eventually stored inside OLR.
Let us move to the next Oracle RAC Interview Questions.
Q3. What do you understand by rolling upgrade?
Answer:
A rolling patch refers to the cluster binaries being applied on the up and running databases of RAC environment. The cluster nodes are rolled one after another where the patched node is unavailable whereas all other instances are in open state.
Q4. What do you understand by cache fusion?
Answer:
This is the basic Oracle RAC Interview Question asked in an interview. The combination of data blocks coming straight from remote database caches and getting shipped to the local nodes so that the requirements for doing a transaction such as a DDL or a DML can be fulfilled.
Q5. What are the uses of RAC?
Answer:
RAC or Real Application Clusters are used to support all the software where aspects such as high availability and grouped level of clustering are expected. Other uses of RAC are:
- Detection of any unwanted results or errors: RAC in itself is efficient in providing a very quick solution to every detected problem. It makes use of auto recovery from the failures way before it is reported to the user.
- Reliability: The RAC helps in ensuring that the server responsible for managing the database is not just dependent on the single point of failure. In other words, it builds and provides a fault tolerant mechanism where even if one node goes down the entire system doesn’t go down and the other provided sources should take its place and thereby providing reliability.
- Continuous Operations: All those planned, as well as unplanned outages, should not affect BAU
- Recoverability: RAC ensures that if there is any failure at any given point of time, the state can be recovered easily at least until the last checkpoint made.
Part 2 – Oracle RAC Interview Questions (Advanced)
Let us now have a look at the advanced Oracle RAC Interview Questions.
Q6. Discuss OEM tools?
Answer:
There are basically two OEM tools: Database Control and Grid Control
Database control:
- A tool used for managing graphics in such a way that the database is able to make its configurations manually
- The server pools are also managed as a result of Oracle Clusterware. The provision is made such that it can be operated and managed from one location itself
- The services related to Oracle RAC and Oracle Clusterware can be managed by making use of Database control tool
Grid control:
- It is a system for delivering a centralized level of management along with administration and configuration related capabilities.
- Higher efficiency and reduction in cost for plans are also provided by Grid control.
Q7. What is the ASM Metadata backup technique?
Answer:
Md_backup is the command which can be used to take ASM metadata backup. It is also used to restore the disk group based configurations if a storage loss for ASM disk group is encountered.
Let us move to the next Oracle RAC Interview Questions.
Q8. Explain the use of interconnect?
Answer:
Data blocks are shipped across a private network from a single instance to a different instance by making use of cache fusion. The data dictionary and the physical blocks are also shared by making use of interconnect.
Q9. The shared storage in RAC consists of some files. Name them. Also, what would be your approach to monitor the protocol being used for interconnect traffic?
Answer:
This is the most asked Oracle RAC Interview Questions in an interview. Control files, Spfiles, Redolog file, and DataFiles are the ones present in the shared storage.
Looking and monitoring the database alert log closely for the stipulated time period especially when the database was initially started up will help you determine the protocol.
Q10. Suppose your remote nodes have some inventory and you are given the task of identifying and verifying them. How will you do that?
Answer:
“Opatch Inventory-all_nodes” is the command which will ensure that you are able to access the data of all the remotely located nodes by just a single node.
Conclusion:
In this post, we have read important Oracle RAC interview questions. The interviewer would be possibly looking at your in-depth level of expertise and the number of hands-on you have on this particular tool. Before you arrive for your day, it is always better to brush up your skills a bit. Please do let us know how much you liked it and keep following our blog.
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