If you're looking for Oracle Exadata Interview Questions for Experienced or Freshers, you are at the right place. There are a lot of opportunities from many reputed companies in the world. According to research, Oracle Exadata has a market share of about 3.6%. So, You still have the opportunity to move ahead in your career in Oracle Exadata Development. Mindmajix offers Advanced Oracle Exadata Interview Questions 2021 that help you in cracking your interview & acquire a dream career as Oracle Exadata Developer.
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Here are frequently asked Oracle Exadata Interview Questions, let's have a look into them.
Exadata is a pre-configured combination of hardware and software which provides a platform to run the Oracle Database.
Exadata comes in the following configuration
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512MB per module.
Each storage cell having 4 modules so its 4X512 MB per CELL
The flash cache is a hardware component configured in the Exadata storage cell server which delivers high performance in reading and writes operations. The primary task of a smart flash cache is to hold frequently accessed data in the flash cache so next time if the same data is required then physical read can be avoided by reading the data from the flash cache.
cellcli – It is a cell command-line utility. We can manage cell storage with the use of cellcli utility. We can say it’s a utility to administer cell storage.
CELLCLI-ALTER CELLCLI-CREATE CELLCLI-DROP CELLCLI-LIST
All the HDD are hot-swappable so if we are using proper redundancy then we can direct remove and replace the new HDD.
Storage software will take care of all the stuff in the background after replacing the HDD.
Spine switch is used to connect or add more Exadata machines to the cluster
Their many methods we can use to migrate DB to Exadata. Below are some of them.
The use of the migration method totally depends on source setup as well as downtime consideration.
Database servers have two options for OS either Linux or Solaris which can be finalized at the time of configuration Cell storage comes with Linux only.
ASR is the tool to manage the Oracle hardware. The full form of ASR is the Auto Service Request. Whenever any hardware fault occurs ASR automatically raises SR in Oracle Support and sends a notification to the respective customer.
It can be done through ILOM of DB or Cell server.
CELLIP.ORA file contains the list of storage server which is accessed by DB server.
EHCC is Exadata Hybrid Columnar Compression which is used to compress data in the Database.
It refers to the fact that part of the traditional SQL processing done by the database can be “offloaded” from the database layer to the storage layer
The primary benefit of Offloading is the reduction in the volume of data that must be returned to the database server. This is one of the major bottlenecks of most large databases.
Cellcli can be used on respective cell storage only.
DCLi (Distributed Command Line Utility) – DCLI can be used to replicate commands on multiple storages as well as DB servers.
IORM stands for I/O Resource Manager which manages the I/Os of multiple databases on storage cell.
We can execute Exacheck and verify the best practice setup on the Exadata machine.
SQL>alter table table_name move compress for query high;
It is not required to take a backup as it happens automatically. Exadata uses an internal USB drive called the Cell boot Flash Drive to take a backup of software.
Before and after any configuration change in Database Machine
Grid Disks are created on top of Cell Disks and are presented to Oracle ASM as ASM disks.
Space is allocated in chunks from the outer tracks of the Cell disk and moving inwards. One can have multiple Grid Disks per Cell disk.
Cell and Grid Disk are logical components of the physical Exadata storage. A cell or Exadata Storage server cell is a combination of Disk Drives put together to store user data. Each Cell Disk corresponds to a LUN (Logical Unit) which has been formatted by the Exadata Storage Server Software. Typically, each cell has 12 disk drives mapped to it.
Four 96G PCIe flash memory cards are present on each Exadata Storage Server cell which provide very fast access to the data stored on it. This is further achieved by also provides a mechanism to reduces data access latency by retrieving data from memory rather than having to access data from disk. Total flash storage of 384GB per cell is available on the Exadata appliance.
It is a feature of the Exadata Software which enhances the database performance many times over. It processes queries in an intelligent way, retrieving specific rows rather than complete blocks. It applies to filter criteria at the storage level based on the selection criteria specified in the query. It also performs column projection which is a process of sending only required columns for the query back to the database host/instance.
The parameter PARALLEL_FORCE_LOCAL can be specified at the session level for a particular job.
Exadata has traditionally run Oracle Linux OS. Recently, Solaris has also been made available on this engineered system.
Cell flash cache read hits
There are 53 wait events that are Exadata specific events.
The X3-8 is comprised of 2 large SMP compute servers while the X3-2 can scale to as many as 8 compute servers as processing requirements increase.
DBRM is the feature of the database while IORM is the feature of storage server software.
Some of the key hardware and software features are:
Approximate 3 hours per Cell and DB server including Infiniband & PDU patching required 1 hour each
It will reduce the risk of storage disk failure
CellCLI> ALTER CELL flashCacheCompress=true
14 storage nodes
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