Oracle Exadata Interview Questionss
Following are some of the most frequently asked Oracle Exadata interview questions in the interview, here are the answers for them.
What is Exadata?
Exadata is pre-configured combination of hardware and software which provides a platform to run the Oracle Database.
What is flash cache and how it works?
The flash cache is a hardware component configured in the exadata storage cell server which delivers high performance in read and write operations.
Primary task of smart flash cache is to hold frequently accessed data in flash cache so next time if same data required than physical read can be avoided by reading the data from flash cache.
What are the types of EHCC?
- Query Low
- Query High
- Archive High
- Archive Low
What is the purpose of spine switch?
Spine switch is used to connect or add more Exadata machine in the cluster
What is ASR?
ASR is the tool to manage the Oracle hardware. Full form of ASR is Auto Service Request.
Whenever any hardware fault occurs ASR automatically raise SR in Oracle Support and send notification to respective customer.
What is the difference between cellcli and dcli?
Cellcli can be used on respective cell storage only.
DCLi (Distributed command Line Utility) – DCLI can be used to replicate command on multipla storage as well as DB servers.
What is the difference between wright-through and write-back flashcache mode?
writethrough –> Falshcache will be used only for reading purpose
writeback –> Flashcache will be used for both reading and writing
Exadata sizing configuation
- Full Rack
- Half Rack
- Quater Rack
- 1/8th Rack
What are the steps to create DBFS?
- Create Directory
- Create Tablespace on database which you are going to use for DBFS
- Create user for DBFS
- Grant required privileges to created user
- Now connect to database with created user
- Create dbfs filesystem by invoking dbfs_create_filesystem_advanced
- Mount file system by starting dbfs_client
What is the difference between DBRM and IORM?
DBRM is the feature of database while IORM is the feature of storage server software.
What is smart flash cache?
Flash cache is the PCIe (Peripheral Components Interconnect Express) card which is plugged into the back end of the storage cell.
How smart scan works?
If any query executes on database server than database server sends the extents and metadata to the storage cell.
Smart scan will scan data blocks to identify relevant rows and columns.
Once data identified by smart scan, it will return to database with only appropriate rows
Once DB server gets the data, it will assemble returned data into result set.
This operation will save the bandwidth as well CPUs and memory cost on database server
as whole sql processing happens on storage server.
What are the pre-requisites to configure ASR?
- Access to My Oracle Support
- Internet connectivity using HTTPS
- Network connectivity from ASR server to Exadata components
Which MOS ID I should refer for latest patch update?
Which tool is used to generate initial configuration files based on customer’s data?
OEDA (Oracle Exadata Deployment Assistance)
What are the unique features of Exadata?
- Smart Scan (Cell Offload)
- Flash cache
- EHCC (Exadata Hybrid Columnar Compression)
- IORM (IO Resource Manager)
- Storage Index
Which all networks available in Exadata?
- Infiniband Network
- ILOM and Management Network
- Client/Public Network
What are the Exadata Health check tools available?
- OEM 12c
What is client or public network in exadata?
Client or public network is used to established connectivity between database and application.
What are the steps involved for initial Exadata configuration?
Initial network preparation
- Configure Exadata servers
- Configure Exadata software
- Configure database hosts to use Exadata
- Configure ASM and database instances
- Configure ASM disk group for Exadata
What is iDB protocol?
iDB stands for intelligent database protocol. It is a network based protocol which is responsible to
communicate between storage cell and database server.
What is LIBCELL?
Libcell stands for Library Cell which is linked with Oracle kernel. It allows oracle kernel to talk with the storage server via network based instead of operating system reads and writes.
Which packaged is used by compression adviser utility?
What is the primary goal of storage index?
Storage indexes are a feature unique to the Exadata Database Machine whose primary goal is to reduce the amount of I/O required to service I/O requests for Exadata Smart Scan.
What is smart scan offloading?
Offloading and Smart Scan are two terms that are used somewhat interchangeably. Exadata Smart
Scan offloads processing of queries from the database server to the storage server.
Processors on the Exadata Storage Server process the data on behalf of the database SQL query. Only the data requested in the query is returned to the database server.
What is checkip and what the use of it?
Checkip is the OS level script which contains IP address and hostname which will be used by Exadata in configuration phase. It checks network readiness like proper DNS configuration, it also checks there is no IP duplication in the network by pinging it which not supposed to ping initially.
Which script is used to reclaim the disk space of unused operating system?
For Linux: reclaimdisks.sh
For Solaris: reclaimdisks.pl
What should be ASM space allocation if backup performed internally?
40% storage space allocation for DATA disk group
60% storage space allocation for RECO disk group
How database server communicates to storage cell?
Database server communicates with storage cell through infiniband network.
Can I have multiple celldisk for one grid disk?
No. Celldisk can have multiple griddisk but griddisk cannot have multiple celldisk
How many FMods available on each flash card?
Four FMods (Flash Modules) are available on each flash card.
Which processes are used by storage software?
- Cellsrv – Cell Server
- MS- management server
- RS – Restart Server
List the steps for replacing the damaged physical flash disk.
- Identify damaged flash disk
- Power off the cell
- Replace flash card
- Power on the cell
- Verify and confirm new flash card
What is smart flash log?
Smart flash log is a temporary storage area on Exadata smart flash cache to store redoes log data.
Which parameter is used to enable and disable the smart scan?
How to check infiniband topology?
We can verify infiniband switch topology by executing verify-topology script from one of our database server.
Can we use HCC on non-exadata environment?
No, HCC is only available data stored on Exadata storage server.
What is resource plan?
It is collection of plan directives that determines how database resources are to be allocated.
What is DBFS?
DBFS stands for Database File system which can be built on ASM disk group using database tablespace.
What are the major steps involved for cell server patching?
- Check and note down existing configuration of cell
- Clean up any previous patchmgr utility
- Verify that the cells meet prerequisite checks
- Patch cell server using patchmgr
- Validation updated cell
What is the purpose of infiniband spine switch?
Spine switch is used to connect multiple exadata database machines.
What is OEM?
OEM is Oracle Enterprise Manager which is centralized tool to monitor and administer systems as well software.
What is offload block filtering?
Exadata storage server filters out the blocks that are not required for the incremental backup in progress so only the blocks that are required for the backup are sent to the database.
Which command is used to monitor BCT?
SQL>select filename,status, bytes from v$block_change_tracking;
How to add memory into database server?
- Power off database server
- Add memory expansion into server
- Power on the server