Getting prepared for Oracle RAC/ASM? Do not panic, we will guide you how and what to answer in your interview. If you are preparing for Oracle RAC/ASM job interview then go through Wisdomjobs interview questions and answers page. Oracle RAC/ASM is the group of clusters that combines several servers such that a single system is formed. Thus single database is used my many systems to access data. Whereas ASM is Automatic Storage Management which manages the database to store the data in it. Instead of administrator manually managing database, ASM will do the job. Almost every organization working with Oracle is using Oracle RAC/ASM. One should know the concepts of Database and Oracle technology. Please have a look at Oracle RAC/ASM interview questions and answers page to win your interview.
Question 1. What Is The Main Purpose Of Oracle Real Application Clusters (rac)?
Answer :
Question 2. Where Are The Clusterware Files Stored On A Rac Environment?
Answer :
The Clusterware is installed on each node (on an Oracle Home) and on the shared disks (the voting disks and the CSR file).
Answer :
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.
Question 4. What Is Required By Oracle Rac Database To Connect To A Network?
Answer :
Question 5. How Is Possible To Install A Rac If We Don’t Have A Cfs?
Answer :
This is possible by using a raw device.
Question 6. What Are The Types Of Connection Load-balancing?
Answer :
There are two types of connection load-balancing: server-side load balancing and client-side load balancing.
Question 7. What Are The Provisions And Resources Provided In The Oracle’s Cloud Server?
Answer :
Question 8. Where Are The Database Software Files Stored On A Rac Environment?
Answer :
The base software is installed on each node of the cluster and the database storage on the shared disks.
Answer :
GRD stands for Global Resource Directory. The GES and GCS maintain records of the status of each datafile and each cached block using global resource directory. This process is referred to as cache fusion and helps in data integrity.
Question 10. Explain The Hardware Architecture Used In Oracle Rac?
Answer :
Question 11. Do You Know Another Cluster Vendor?
Answer :
HP Tru64 Unix, Veritas, Microsoft
Question 12. What Are The Performance Views In An Oracle Rac Environment?
Answer :
We have v$ views that are instance specific. In addition we have GV$ views called as global views that has an INST_ID column of numeric data type.GV$ views obtain information from individual V$ views.
Question 13. What Is The Function Of Cache Fusion In Oracle Rac?
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Question 14. What Kind Of Storage We Can Use For The Rac Database Storage?
Answer :
Question 15. What Is A Crs Resource?
Answer :
Oracle Clusterware is used to manage high-availability operations in a cluster. Anything that Oracle Clusterware manages is known as a CRS resource. Some examples of CRS resources are database, an instance, a service, a listener, a VIP address, an application process etc.
Question 16. How Is Clustered Database Important In Oracle Rac Architecture?
Answer :
Question 17. What Is An Ocfs2?
Answer :
The OCFS2 is the Oracle (version 2) Cluster File System which can be used for the Oracle Real Application Cluster.
Question 18. How Do We Remove Asm From An Oracle Rac Environment?
Answer :
We need to stop and delete the instance in the node first in interactive or silent mode. After that ASM can be removed using srvctl tool as follows:
Question 19. Describe The Oracle Real Application Clusters Architecture?
Answer :
Answer :
A cluster File System (CFS) is a file system that may be accessed (read and write) by all members in a cluster at the same time. This implies that all members of a cluster have the same view.
Question 21. What Is The Use Of Ocr?
Answer :
Oracle Clusterware manages CRS resources based on the configuration information of CRS resources stored in OCR (Oracle Cluster Registry).
Question 22. What Are The Key Components Of Oracle’s Maximum Availability Architecture?
Answer :
Question 23. What Kind Of Storage We Can Use For The Shared Clusterware Files?
Answer :
Question 24. How Does An Oracle Clusterware Manage Crs Resources?
Answer :
Oracle Clusterware manages CRS resources based on the configuration information of CRS resources stored in OCR (Oracle Cluster Registry).
Answer :
In Oracle Database 10g/11g there are two types of instances: database and ASM instances. The ASM instance, which is generally named +ASM, is started with the INSTANCE_TYPE=ASM init.ora parameter. This parameter, when set, signals the Oracle initialization routine to start an ASM instance and not a standard database instance. Unlike the standard database instance, the ASM instance contains no physical files; such as logfiles, controlfiles or datafiles, and only requires a few init.ora parameters for startup.
Upon startup, an ASM instance will spawn all the basic background processes, plus some new ones that are specific to the operation of ASM. The STARTUP clauses for ASM instances are similar to those for database instances. For example, RESTRICT prevents database instances from connecting to this ASM instance. NOMOUNT starts up an ASM instance without mounting any disk group. MOUNT option simply mounts all defined diskgroups
For RAC configurations, the ASM SID is +ASMx instance, where x represents the instance number.
Question 26. What Are The Key Benefits Of Asm?
Answer :
ASM provides filesystem and volume manager capabilities built into the Oracle database kernel. Withthis capability, ASM simplifies storage management tasks, such as creating/laying out databases and disk space management. Since ASM allows disk management to be done using familiar create/alter/drop SQL statements, DBAs do not need to learn a new skill set or make crucial decisions on provisioning.
The following are some key benefits of ASM:
Question 27. How Does Database Connects To Asm Instance?
Answer :
The database communicates with ASM instance using the ASMB (umblicus process) process. Once the database obtains the necessary extents from extent map, all database IO going forward is processed through by the database processes, bypassing ASM. Thus we say ASM is not really in the IO path. So, the question how do we make ASM go faster…..you don’t have to.
Question 28. What Init.ora Parameters Does A User Need To Configure For Asm Instances?
Answer :
The default parameter settings work perfectly for ASM. The only parameters needed for 11g ASM:
Question 29. How Does The Database Interact With The Asm Instance And How Do I Make Asm Go Faster?
Answer :
ASM is not in the I/O path so ASM does not impede the database file access. Since the RDBMS instance is performing raw I/O, the I/O is as fast as possible.
Question 30. Do I Need To Define The Rdbms Filesystemio_options Parameter When I Use Asm?
Answer :
No. The RDBMS does I/O directly to the raw disk devices, the FILESYSTEMIO_OPTIONS parameter is only for filesystems.
Question 31. Why Oracle Recommends Two Disk Groups?
Answer :
Oracle recommends two diskgroups to provide a balance of manageability, utilization, and performance.
Answer :
For VLDBs you will probably end up with different storage tiers; e.g with some of our large customers they have Tier1 (RAID10 FC), Tier2 (RAID5 FC), Tier3 (SATA), etc. Each one of these is mapped to a diskgroup.
Answer :
For 11g ASM/RDBMS it is recommended to use 4MB ASM AU for disk groups. See Metalink Note 810484.1
Question 34. Would It Be Better To Use Bigfile Tablespaces, Or Standard Tablespaces For Asm?
Answer :
The use of Bigfile tablespaces has no bearing on ASM (or vice versa). In fact most database object related decisions are transparent to ASM.
Question 35. What Is The Best Lun Size For Asm?
Answer :
There is no best size! In most cases the storage team will dictate to you based on their standardized LUN size. The ASM administrator merely has to communicate the ASM Best Practices and application characteristics to storage folks :
• Need equally sized / performance LUNs
• Minimum of 4 LUNs
• The capacity requirement
• The workload characteristic (random r/w, sequential r/w) & any response time SLA
Using this info , and their standards, the storage folks should build a nice LUN group set for you.
Answer :
For clarification
• Separate Oracle Home for ASM and RDBMS.
• RDBMS instance connects to ASM using OSDBA group of the ASM instance.
Thus, software owner for each RDBMS instance connecting to ASM must be a member of ASM's OSDBA group.
• Choose a different OSDBA group for ASM instance (asmdba) than for RDBMS instance (dba)
• In 11g, ASM administrator has to be member of a separate SYSASM group to separate ASM Admin and DBAs.
Question 37. Can My Rdbms And Asm Instances Run Different Versions?
Answer :
Yes. ASM can be at a higher version or at lower version than its client databases. There’s two:
components of compatiblity: Software compatibility
Diskgroup compatibility attributes: compatible.asm, compatible.rdbms.
Question 38. Where Do I Run My Database Listener From; I.e., Asm Home Or Db Home?
Answer :
It is recommended to run the listener from the ASM HOME. This is particularly important for RAC env, since the listener is a node-level resource. In this config, you can create additional [user] listeners from the database homes as needed.
Question 39. How Do I Backup My Asm Instance?
Answer :
Not applicable! ASM has no files to backup, as its does not contain controlfile,redo logs etc.
Question 40. When Should I Use Rman And When Should I Use Asmcmd Copy?
Answer :
RMAN is the recommended and most complete and flexible method to backup and transport database files in ASM.
ASMCMD copy is good for copying single files
• Supports all Oracle file types
• Can be used to instantiate a Data Guard environment
• Does not update the controlfile
• Does not create OMF files
Question 41. I'm Going To Do Add Disks To My Asm Diskgroup, How Long Will This Rebalance Take?
Answer :
Rebalance time is heavily driven by the three items:
1) Amount of data currently in the diskgroup
2) IO bandwidth available on the server
3) ASM_POWER_LIMIT or Rebalance Power Level
Answer :
Given that the new and old storage are both visible to ASM, simply add the new disks to the ASM disk group and drop the old disks. ASM rebalance will migrate data online.
Answer :
No. Cross-platform disk group migration not supported. To move datafiles between endian-ness platforms, you need to use XTTS, Datapump or Streams.
Question 44. How Does Asm Work With Multipathing Software?
Answer :
It works great! Multipathing software is at a layer lower than ASM, and thus is transparent.
You may need to adjust ASM_DISKSTRING to specify only the path to the multipathing pseudo devices.
Question 45. Is Asm Constantly Rebalancing To Manage “hot Spots”?
Answer :
No.ASM provides even distribution of extents across all disks in a disk group. Since each disk will equal number of extents, no single disk will be hotter than another. Thus the answer NO, ASM does not dynamically move hot spots, because hot spots simply do not occur in ASM configurations. Rebalance only occurs on storage configuration changes (e.g. add, drop, or resize disks).
Question 46. What Are The File Types That Asm Support And Keep In Disk Groups?
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Question 47. List Key Benefits Of Asm?
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Question 48. What Is Asm Striping?
Answer :
ASM can use variable size data extents to support larger files, reduce memory requirements, and improve performance.
Each data extent resides on an individual disk.
Data extents consist of one or more allocation units.
The data extent size is:
ASM stripes files using extents with a coarse method for load balancing or a fine method to reduce latency.
Question 49. How Many Asm Diskgroups Can Be Created Under One Asm Instance?
Answer :
ASM imposes the following limits:
Question 50. What Is A Diskgroup?
Answer :
A disk group consists of multiple disks and is the fundamental object that ASM manages. Each disk group contains the metadata that is required for the management of space in the disk group. The ASM instance manages the metadata about the files in a Disk Group in the same way that a file system manages metadata about its files. However, the vast majority of I/O operations do not pass through the ASM instance. In a moment we will look at how file I/O works with respect to the ASM instance.
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