INTERVIEW QUESTIONS PART-2

·         Difference between awr,ash and addm report?

·         Main things required to configure RAC?

·         Difference Between public, private,vip and scanip?

·         What is active dataguard?

·         Table to find the gap in applying archivelog.

·         12c features?

·         Database tuning?

·         What are the things have to look in AWR?

·         How to derive the size of logical, physical n memory to create a database for oltp and datawarehouse environment and things to consider while creating it?

·         Where the statistics are stored in database?

·         How to monitor RAC?

·         What is the usage of CRS?

·         How to check the availability of the nodes in RAC?

·         What is DB time and CPU time?

·         What are the elements present in the output of TOP command?

·         What is netstat command do?

·         How will you monitor the OS?

·         What is Hugepage?

·         How to configure three node RAC?

 

·         Your Day by day activities?

·         New process parameter in 12c?

·         Diff between 11g and 12c listener different?

·         How to take consistent backup in datapump ?

·         How to improve datapump speed?

·         Diffe bW traditional and datapump ?

·         How to do upgrade ? Steps

·         Rolling patches steps

·         RAC startup sequence?

·         RAC components?

·         Standalone to RAC migration ?

·         DC Dr dril activity ?

·         DataGuard performance modes ?

·         RAC swithchover steps,

·         Active DataGuard?

·         Standby redolog files is mandatory? Or not required on standby

·         I/o error ? In standby alert longs what would be reason ?

·         Required files and parameters to configure standby env?

·         Which algorithm will use for TDE configuration ?

·         How tde will work ?

·         Real time scenarios?

·         Like redolog file curruption ?

·         After resetlogs with open db ? If we required earlier stage what steps to be taken

 

·         Ok I’m ?

·         ASM types disks ? And

·         How to check asm after added by os team ? Where you will check

·         What is maximum size of asm disk, asm disk group?

·         Datafile size depends upon ?

·         Performance tuning ?

·         Exadata components ?

·         Basics of golden date architecture

·         Oracle 12c features and snapshot standby concepts

·         Ora 1555 error ? Solution

·         Rman backup types ?

 

·         How do you find cluster active version ?

·         What is HAIP? how to check whether its configured or not ?

·         What is cluster interconnects ? What protocol they use ?

·         what is RDP & UDP & TCP ?

·         What is cache fusion ?

·         Participating nodes in a cluster?

·         How to find subnet mask, Virtual IP & Private  IP & public ip at cluster level ?

·         Waht is GIMR ?

·         What is the use of MGMTDB database in 12c? explain its background process ? functions ? Does it run on all nodes ? what happens when u remove MGMGTDB from cluster ?

·         Flex ASM ?

·         what is semaphore ? parameters  related to it ? semmns,  semmsl, semmni, semmnu

·         multi-threading concept usage in Oracle ? and what parameter changes are required to enable it ?

·         what is shared memory structure ?

·         Functions of  CSSD ? CRSD ? EVMD ? which background proess runs on root and Oracle ?

·         END of REDO ?

·         what is RBA ?

·         What is RBA ? you can see in alert log ? what does RBA denotes ?

·         Diff between instance recovery & crash recovery ?

·         what is Block change tracking ? in RMAN?

·         which process writes data from database files to database buffer cache ? not DBWR !!! DBWR writes dirty block from Buffer cache to datafiles.

·         what is dirty block ?

·         what is checkpoint ?

·         When an user issues SELECT * FROM EMP ? explain how oracle fetches data to the user ?

·         What is Hard parse & soft parse ?

·         what is ROWID ?

·         what is Average row length in dba_indexes view ?

·         what is Latch & Lock ?

·         what is OPATCH Auto -check all options ?

·         What is Opatch apply & Opatch Napply

·         what is OPLAN ?

·         how to check opatch will get succeed before applying it on Oracle HOME ?

·         what is node eviction ?

·         How to check whether a table required to be analyzed or not ?

·         what is stored outline, sql profile , SQL baseline plans ?

·         what is Automatic memory management ?

·         how to check database names registered in the cluster ?

·         standby_file_management parameter ?

·         CLuster startup sequence ?

·         What is OCR ? voting disk ? how many voting disks are required in an cluster ?

·         what is scan listener ?

·         What is local listener and how it differs from SCAN ?

·         what is DNS ? and how its used in SCAN? other than DNS configuration what alternate method can scan use to function ?

·         ASM redundancy levels ?

·         ASM AU ?

·         What is Quorum disks ?

·         ASMLIB ?

·         ASM Multipath ?

·         ASM Stripping ?

·         what is partner disk ?

·         Rebalance phases in ASM & ASM Background process ?

·         basic init parameter for ASM ?

·         what is ACFS ? hoe to create an ACFS mount point ? hoe to mount it in server ? what are the things can be stored in ACFS ? BLOB/CLAB can be stored ? adding ACFS file system to Oracle restart ?

·         What is Oracle re-start ?

·         what id DFBS File system ?

·         What is flashback database ? what are the things can be flashbacked ? can we flashback a DML transaction ?

·         what is restore point ?

·         sysadm & sysdba difference

·         what is DCLI & CELLCLI difference ?

·         What is ZFS file system ?

·         diskgroup creation pre-requsite and create commands ? how to add a new disk to a disk group ?

·         what is disk repair time ?

·         can we modify rebalance power limit while the re-balance is in progress ?

·         how to check a disk status in a disk group ?

·         exadata patching steps ? compute node update  ? Opatch on GRID & RDBMS home , Infiband network patching ?

·         what is patchmanager ? option used in patch manager ?

·         what cell server patching is initiated in compute node?

·         upgrading the database to higher version ? steps? methodology used ?

·         DBUA ?

·         what is timezone upgrade ?in DBUA ?

·         how to check Database component status post upgrade ?

·         CLUfy command and its usage?

·         what are the functions of cluvfy ? cluvfy - help

·         which process transfers logfiles from primary to standby server ?

·         what is MRP ?

·         use of standby redolog file ?

·         Datagaurd modes and parameters to be set to activate it?

·         What is online redolog file and what happens when an current redolog file or active/inactive redolog file gets corrupted. ?

·         how to upgrade a single DB component in an database ?

·         what is GPNP profile in rac ? location ? and its contain ?who updates GPNP profile ?

·         how is gpnp profile used by clusterware ?

·         how to identify the clustername ?

·         what is thread in gv$logfile/ gv$log ?

·         how to read/analyze top command output ?

·         how to identify Node eviction RCA ?

·         exawatcher/OS Watcher  logs retention time ? can we modify it ? It can monitor IB switches and databases.Diskinfo, IBCardInfo IBprocs Iostat LGWR Lsof MegaRaidFW Meminfo There is difference between original OSW and Exadata versions (OSW and EW). Original OSW store historical files in the *.dat, but the Exadata's version store files in bzip2 : How long  store the history:  looking the code /opt/oracle.ExaWatcher/ExaWatcherCleanup.sh

 

 

·         Where to find the exadata ILOM Ip's information ? /opt/oracle.Support/onecommand/dbm.dat file

·         What is OLR ? use of it ?

·         How does Oracle database instance and ASM instance gets started after reboot ? or node eviction if the ASM spfile is present inside it  ?

·         Any issues faced in Pathcing ? if so actions taken ? how to avoid errors/issues before applying patch on GRID/RDBMS Home?

·         Any issues while upgrading a database ?

·         can we have same name for two databases in a cluster?

·         applying patch with minimal downtime strategy ? rolling and non-rolling methods ?

·         What is datapatch ? With Oracle 12c the SQL commands belonging to one patch are not installed by catbundle.sqlbut by the 揹atapatch? tool, which is located in the OPatch directory. The result of the 揝QL Apply? can queried in the view dba_registry_sqlpatch, i.e. like this:

 

·         SQL> SELECT patch_id, version, status, bundle_id, bundle_series           

o   FROM dba_registry_sqlpatch;

 

 

·         diference between crsctl stop crs and crsctl stop cluster -all ?

·         what is IPMI ?

·         what is ADVM ?

·         how to copy files between asm instances ?

·         if node is down, what will happen to acfs on that node ?

·         i have 50gb of table to be selected, 30g of db buffer cache and 40gb of sga ? what will happen to my query ?

·         what is global inventory and local inventory ?

·         what is OCSSD ? what is the primary operation for it ?

·         what is client side load balancing and server side load balancing ?

·         what is scan vip and scan listener ?

·         what is TAF ? different types of TAF ?

·         in which diskgroup we can place voting disk ?

·         what is variable extent space management in ASM ?

·         what are the phases of rebalance how will you analyse it ?

·         what is snapshot controlfile ?

·         what is options available in dbnodeupdate.sh ? -u,-l,-p,-c

·         what is sundiag, tfactl and exacheck ? Sundiag is used to diagnose the problems in the disks in Exadata. /opt/oracle.SupportTools/sundiag.sh.tfactl diagcollect command to perform on-demand diagnostic collection. You can specify a specific time of an incident or a time range for data to be collected, and determine if whole files that have relevant data should be collected or just a time interval of data from those files. Exacheck tool checks your Oracle Exadata Database Machine configuration, software, critical issue and provides a Maximum Availability Architecture score.  It is required to run before and after Exadata patching and is good practice to run on a frequent basis and review the recommendations.

 

 

·         how many compute nodes in a full rack exadata ? 8

·         what is locally managed tablespace and dictionary managed tablespaces ?

·         how to identify subnet mask, private ip, vip and public ip in cluseter ?

·         what is nested loop , hash join ?

·         what is ora-1555, ora-4031?

·         what is log file sync ?

·         what is free buffer wait and how will you troubleshoot on it ?

·         which process is used for incoming remote requests in RAC ?

·         why we should turn on archive log for flashback ?

·         how will you recover when table is corrupted ?

·         user A started a transaction on 9 AM and it is still running, in between around 9:20 user B queried select query on that transaction running table, will he see the old data or new data ?

·         what will happen when we give commit ?

·         why commit is faster ?

·         what will happen when we give rollback ?

·         if one of my voting disk is corrupted, what will happen to my cluster ? and how will you recover voting disk ?

·         if crs is not coming up, what will be your action plan to check ?

·         why we need standby redologs ?

·         what is FSFO ? fast start failover

·         how will you change protection mode in dataguard ? which parameter will you change ?

·         what is active dataguard ?

·         what is snapshot standby and when we convert from physical to snapshot standby what will happen in background ?

·         primary db and standby db running in 12.1 version, i am upgrading standby to 12.2 ? will it be possible ?

·         what will happen when we give tablespase begin backup mode ?

·         ways to find master node in cluster ?

·         what is difference between resetlogs and noresetlogs ?

·         what is database incarnation ?

·         what is difference between SYNC to ASYNC and AFFIRM to NOAFFIRM ?

·         what is hugepages ?

·         why we prefer ASMM over AMM ?

·         what are the prerequisites to perform switchover ?

·         what will happen when we set standby_file_management to manual ?

·         what is materialised view ?

·         how do you implement flex ASM ?

·         what is timezone version in 11g and 12c ? 11g - 14 and 12c - 18

·         how you add vip to a cluster ?

·         which process is used to push the targets from oms to OEM ?

·         what is force logging ?

·         explain some wait events ?

·         what is cursor sharing ?

·         what is large pool and why we need it ?

·         what is sort_area_size parameter ?

·         difference between keep pool and in memory ?

·         how do you add node to a cluster ?

·         non-asm to asm ?

·         12c new features ?

·         12.2 new features ?

·         what is shmmax and shmall ?

·         how to check smart scan enabled in db ?

·         what is cell offload processing ?

·         i have 1tb of data and want to export it. i dont want to use parallel option . how will you export in faster way ?

·         how do you take consistent export ? which parameter you use ?

·         non-asm to asm in 12c ?

·         how many ip we need when we configure HAIP ?

·         When to use SET DBID in RMAN?

·         My query was fine last week and now it is slow. Why?

·         What to Look for in AWR Report and STATSPACK Report?

·         what is Dynamic Sampling OPtimiser(optimizer_dynamic_sampling) ?

·         what is DB_FILE_MULTIBLOCK_READ_COUNT ?

·         what is index skip scan, index fast scan and index scan ?

·         What is SCN?

·         what is pga and uga ?

·         what is split brain ?

·         what is diskmon and evmd process ?

·         checking smart flash cache mode ?

·         how will convert writeback to writethrough or writethrough to writeback ? rolling and non-rolling method\

·         how will you find when the disk is fault in storage node ?

·         what are the modes in disk in storage node ? NORMAL , SYNCING and FAULT modes

·         How does OCSSD starts if voting disk & OCR resides in ASM Diskgroups?

·         RAC WaitEvent ?

·         what is miscount ?

·         Can we start the 10g database from 11g binaries?

·         How will you convert single instance to RAC

·         How will you find out execution plan for a query in shared pool?

·         How many threads & redo log groups does standby have if i have 8 node RAC?

·         Why we shud not use bitmap index?

·         Steps for RMAN active duplicate ?

·         what is exclusive lock & how it get acquired ?

·         Whats the use of max availability mode in DG?

·         what is row chaining and row migration ?

·         difference between celladmin, cellmonitor and root ?

·         How primary is getting converted to standby in failover scenarios?

·         Archive is corrupted before shipping to standby , how will u recover?

·         if user is connectiing to a db in RAC, how scan listener work for it ?

·         if we have 2 node rac, we have 3 scan ips usual. but all application connecting to node2 not to node1 .. how will you troubleshoot it ?

·         RAC to nonRAC steps ?

·         migration of OCR from RAC to nonASM ?

·         if rootcrs.pl is failed in RAC, what will be your action plan ?

·         how to change network ip for a node in RAC ?

·         what is observer in FSFO ?

·         can we add multiple size of disk in diskgroup ?

·         on jan1 standby is out if sync, jan 4th added a new datafile, jan 7th manager is complaining that database is out of sync . what will you do ?

·         we have 1.5g of redo log in primary and after 6 months we created standby db which consists of 1g  of standby redo log . will the db in sync ?

·         if we have ocr and voting disk in ASM. can we shutdown the asm instance ?

·         ocr and voting disk must be accessible but the asm should be down . what will you do ?

 

·         How do you check and repair acfs filesystem ?

·         rootcrs.pl -lock and rootcrs.pl -unlock ?

·         what is far sync ?

·         what is gds ?

·         where do you specify block size in dbca ? if we select custom database template.

·         can you create tablespace with diferrent block size ?

·         what might be the reason if your awr snapshots are missing !?

·         if you are updating a table data the undo information is stored for read consistency ? where the information is stored in oracle blocks for read and write consistency ? Check ITL !! Interested transaction lists !

·         Tuning PGA memory management ,check work area size types like optimal ,one pass ,multi pass concepts

·         soft parse and hard parse

·         clustering factor in indexes !?

·         how to change private IP for the whole cluster ?

·         how to stop whole cluster from one node ?

·         OCR. location

·         how to add voting disk ?

·         OLR location

·         dropping current redolog is lost or corrupted how to start the database ?

·         recover database until cancel option ?

·         database upgrade and loss of database component ?or need to upgrade a single database component in database ?

·         real time apply in standby database ?

·         how to delete gaurateed restore point in read only database ?

·         if you flashback your primary database what steps you take to make your standby sync with primary

·         how to move or steps to move your database from max performance to max protection mode ?

 

 

·         find the location of ASM spfile if the ASM is down ? gpnptool getpval -asm_spf

·         find GPnP Deamons are running on the local node ? gpnptool lfind

·         archive log corrupted in standby and out of sync with primary. MEanwhile datafile has been added in primary, .. how will you make standby in sync with primary.?

·         in tts how will you check if tablespace has dependent with other tablespaces ?

·         how do you replace ocr ?

·         what is the use of calibrate commmand ?

·         if primary is failed over to standby. Existing primary db came up, do the db will be in sync with new primary (standby) ? how do you do that ?

·         shall we create a restore point in standby ?

·         What are wait events in RAC ?

·         What are GC buffer busy waits ? and other RAC related wait events.?

·         Do a wait event cause node eviction ? if so can you share your experiences on it !

·         what is LNS LMOd GCS GES GRD ? in RAC ?

·         if multiple instances require same set of data blocks how the RAC process it ? and how can be contention handled in such scenarios?

·         what is main advantage of using exadata than normal RAC system ? share some insights !

·         There are 30 to 40 indexes on a table how to find which indexes are used for retrieving data and used widely in explain plan and others are dead weight to the database!?

·         how to run an update statement for a table which updates nearly 500 million rows without impacting the database or locking the database? or how to improve performance of the update

·         what are the checks you do for a normal production database ? daily checks ?

·         how to overcome I/O for a table ? disk I/O where wil you check disk I/O in awr reports ?

·         ways to make rman backups faster ?

·         Control file can't be recovered from the backup how to start the database in such scenarios ?

·         what does happen when u kigive shutdown immediate and shut abort ? explain what happens at background

·         An user complains that he was facing issue a while ago and the transactions were hanging. and it's fine after few minutes? what steps you take to analyze the issue ?

·         Is one voting disk enough for RAC how to add voting disk to new diskgroup with normal or high redundancy ?

·         RAC: Frequently asked questions RAC FAQ DOC I'd - 220970.1

 

• How do you check which data file is corrupted ?
• v$database_block_corruption
• System data file is corrupted and there is only RMAN recent incremental backup available.
• 10 "users" data files are there. 1 is corrupted. Strictly no down time.
• Client says suddenly performance gone down. First what you'll check ?
• What is your backup strategy when the database size is 30+ TB.
• How to check gaps, long running queries, datapump status, rman struck status.
• Database is down and not starting up.
• You are on a call, a person from different team asked for SYSDBA privileges to his user. How will you manage ? What is your action ?
• What happens if you set a) Cursor_sharing = exact b) cursor_sharing = force c) what is default
• Application is not responding when a button is clicked, but application is fine. What will you check in database end.
• Dump file is 1gb but when imported it is going up to more than 150gb. What might be the reasons ?
• Can you create indexes on temporary tables ?
• You don't have direct access to the DB server, but you need dump for schema difference on high priority. What and all options you have to get only the skeliton of the schema ?
• You have recovered database, but DB prompts " Alter database open resetlogs" Is this safe ? Is it recommend ?