Exadata Faq's

Exadata Faq's

Oracle Exadata Cloud Machine Features and Benefits?

Features:
-Enables Oracle RAC Databases (11.2.0.4 or 12.1.0.2) on Exadata
-Highly proven database hardware platform with NVMe Flash, InfiniBand networking, and the fastest servers
-All Database Options, Enterprise Manager Database Packs available
-Intelligent database platform with Smart Database Algorithms in storage, networking, and compute
-Advanced database cloud platform with subscription based pricing and real-time online capacity bursting
-Comprehensive database management through Oracle Enterprise Manager, as well as Cloud-based self-service
-Flexible cloud that can be deployed in Oracle's public cloud or inside the customer's data center with Oracle managing all infrastructure
-Simple and straightforward migration to the cloud - software and hardware are identical and 100 percent compatible
-All Exadata performance optimizations available
-Full compatibility with on-premises Oracle Databases
-Full root OS and SYSDBA access to manage your databases
-Supports OLTP / analytic / mixed workload databases
-Enables consolidation, Test/Dev, proof-of-concept, certification, etc.
-Secured network access; customer databases run in separate VM
-Easy and rapid database provisioning in a few clicks
-Cloud automation software reduces administration
Subscribe to only the compute cores needed by the application

 Benefits:
-Metered Service: Providing the flexibility to meet your business needs
-Proven: Exadata already running in thousands of mission-critical sites worldwide
-Highly Available: Run your database across 2 to 8 nodes
-Capacity on Demand: Between 16 and 272 cores
-Cost effective: pay only for the CPU cores you enable.
-Rapid Provisioning: dedicated, pre-built, fully functional Exadata environment
-Ready to use: to deploy your Oracle databases in Cloud
-All inclusive: Memory, storage, and network resources are all included
-Optimized for performance: All the Exadata Database Machine features
-Complete: Oracle Database Enterprise Edition—Extreme Performance options

Why Exadata for Oracle Databases?

-Exadata is engineering system, with inbuilt provide software+hardware with intelligence.
-Exadata is high performance and high available pre-configured device.
-It consists of servers,storage networking and software in single pre-configured box which is massively scalable, secure and redundant.
-Multiple compression tiers are available on Exadata which can help customer to compress data as per business requirement to save storage space.
-Implementation time is very less compare to non-Exadata systems as it's comes as pre-configured and pre-tested.
-In case on any issue with the Exadata than we need to communicate with only single vendor which doesn't required to contact multiple vendor like non-Exadata setup so solution of issue could be done quicker.
-Only DMA (Database Machine Administrator) would be required to manage the Exadata so it can manage with lower TCO which reduce the huge cost of manageability.
-Exadata provides extreme performance for both DW and OLTP databases which is making it and ideal platform for database consolidation.
-Today we are facing issue of high I/O on database server which has been reduced on Exadata using smart scan feature which will offload SQL process to the storage server hence only required data would be transferred to the Exadata.
-Exadata Smart Flash Cache transparently caches hot data to fast solid-state storage, improving query response times and throughput.
-Exadata's massively parallel grid is ideally suited for consolidating data warehousing and OLTP applications, and Exadata quality-of--service resource management capabilities ensure fast response times for all users.
-Expandable storage capacity without effecting database services.
-Exadata is a solution with standard components implemented for many customers which can guarantee maximum availability.
-With the use of IORM we can prioritize the I/Os based on the business criticality and requirement.
-Smart flash cache log is used to write redo data which quicker than the storage disk so we can achieve faster acknowledgement and query response.
-Ability to increase processing capability both vertically and horizontally
-This is Oracle h/w so we can also get benefit of using ASR which will log a service request automatically if any thing goes wrong in

Exadata hardware.
-It's architecture can support cloud computing.
-Fault tolerance and no single point of failure.
-All software installed with standard , tuned and optimized configuration.

What is Exadata?
Exadata is pre-configured combination of hardware and software which provides a platform to run the Oracle Database.

Key components of Exadata?
1. DB Server
2. Cell Storage
3. Infiniband Switch
4. Cisco Switch
5. PDU

Features of Exadata?
1. Smart Scan
2. Smart Flash Cache
3. IORM
4. Storage Index
5. EHCC (Exadata Hybrid Columnar Compression)

Exadata Sizing?
Exadata comes in follwing configuration
1. Full Rack
2. Half Rack
3. Quater Rack
4. 1/8th Rack

What is storage index and how it works?
1. Storage Indexes consist of a minimum and a maximum value for up to eight columns. This structure is maintained for 1MB chunks of storage (storage regions).
2. Storage Indexes are stored in memory only and are never written to disk.
3. Storage Index filter out data from the consideration.

Which protocol used by ASR to send notification?
SNMP
Simple Network Management Protocol, a set of protocols for managing complex networks.

Is manually intervance possible in storage index?
No

What are the options to update cell_flashcache for any object?
KEEP
DEFAULT
NONE

What is the default size of smart flash log?
512MB per module.
Each storage cell having 4 modules so its 4X512 MB per CELL

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 is cellcli?
cellcli – It is cell command line utility. We can manage cell storage with the use of cellcli utility. We can say it’s utility to administer cell storage.
CELLCLI-ALTER CELLCLI-CREATE CELLCLI-DROP CELLCLI-LIST

Types of EHCC?
1. Query Low
2. Query High
3. Archive High
4. Archive Low

Which package can be used to estimate the compression ration of table?
DBMS_COMPRESSION

Background services of Cell Server?
MS- Management Server
cellsrv – Cell Server
RS – Restart Server

How to replace faulty HDD in Exadata Storage?
All the HDD are hot swapable so if we are using proper redundacny than we can direct remove and replace new HDD. Storage software will take care all the stuffs in background after replacing the HDD.

How many disk comes with in a storage cell?
12

What is the purpose of spine switch?
Spine switch is used to connect or add more Exadata machine in the cluster

How to migrate database from normal setup to Exadata ?
There many methods we can use to migrate DB to Exadata. Below are some of them.
1. Export/Import
2. Physical Standby
3. Logical Standby
4. Transportable Tablespace
5. Transportable Database
6. Golden gate
7. RMAN cold and hot backup restoration
8. Oracle Streams
Use of migration method is totally depends on source setup as well as downtime consideration.

Exadata shutdown and start-up procedure?
Shutdown Procedure:
Stop Database and Listener
Stop Cluster
Shutdown Database Servers
Shutdown Cell Storage
Shutdown all the switches
Remove powers from PDUs
Start-up procedure would be in reverse order.

How many database servers comes in 1/8th rack and quarter rack?
2

How many cell storage comes in full rack exadata machine?
14

Can we use flash disk as ASM disk?
Yes

Which protocol used for communication between database server and storage server?
iDB protocol

Which OS is supports in Exadata?
Database servers has two option for OS either Linux or Solaris which can be finalized at the time of configuration Cell storage comes

with Linux only.

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.

How to integrate Exadata with OEM 12c?
1. Install OEM agent on DB server
2. Launch auto discovery with the use of One Command XML file
3. Specify required credentials for all the components
4. Review Configuration
5. Complete the setup

How to upgrade firmware of Exadata components?
It can be done through ILOM of DB or Cell server.

Where we can define which cell storage can be used by particular database server?
CELLIP.ORA file contains the list of storage server which is accessed by DB server.

What are the Exadata Health check tools?
1. Exacheck
2. sundiagtest
3. oswatcher
4. OEM 12c

What is EHCC?
EHCC is Exadata Hybrid Columnar Compression which is used to compress data in the Database.

What is offloading and how it works?
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.

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 IORM and what is its role in Exadata?
IORM stand for I/O Resource Manager which manages the I/Os of multiple database on storage cell.

How we can check whether oracle best practice has been configured on Exadata?
We can execute Exacheck and verify the best practice setup on Exadata machine.

How many networks required in Exadata?
1. Public/Client Network — For Application Connectivity
2. Management Network — For Exadata H/W management
3. Private Network — For cluster inter connectivity and Storage connectivity

What is the command to enable query high compression on table?
SQL>alter table table_name move compress for query high;

How to take cell storage software backup?
It is not required to take a backup as it happens automatically. Exadata use internal USB drive called the Cellboot Flash Drive to take backup of software.

What is the difference between wright-through and write-back flashcache mode?
1. writethrough –> Falshcache will be used only for reading purpose
2. writeback –> Flashcache will be used for both reading and writing

Which feature of Exadata is used to eliminate disk IO?
Flash Cache

What is the capacity of Infiniband port?
40 Gbps

What is the difference between high capacity and high performance disk?
1. High capacity disk comes with more storage space and less rpm (7.5k)
2. High Performance disk comes with less storage and high rpm (15k)

When one should execute Exacheck?
Before and after any configuration change in Database Machine

What is grid disk?
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.

Which network is used for RAC inter-connectivity?
Infiniband Network

What are the steps to create DBFS?
1. Create Directory
2. Create Tablespace on database which you are going to use for DBFS
3. Create user for DBFS
4. Grant required privileges to created user
5. Now connect to database with created user
6. Create dbfs filesystem by invoking dbfs_create_filesystem_advanced
7. Mount file system by starting dbfs_client

Which migration methodology available if want to migrate from high endian to low endian OS architecture?
1. Golden Gate
2. Transportable Tablespace
3. Incremental Transportable Tablespace
4. Data Pump

What is a Cell and Grid Disk?
Cell and Grid Disk are a logical component 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.

What is Flash cache?
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 mechanism to reduces data access latency by retrieving data from memory rather than having to access data from disk. A total flash storage of 384GB per cell is available on the Exadata appliance.

What is Smart Scan?
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 the complete blocks. It applies filtering 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.

What are the Parallelism instance parameter used in Exadata?
The parameter PARALLEL_FORCE_LOCAL can be specified at the session level for a particular job.

What are the ways to migrate onto Exadata?
1. Depending on the downtime allowed there are several options:
2. Traditional Export/Import
3. Oracle DataGuard
4. Tablespace transportation.
5. Goldengate Replication after a data restore onto Exadata.

What operating systems does Exadata support?
Exadata has traditionally run Oracle Linux OS. Recently, Solaris has also been made available on this engineered system.

Which statistic can be used to check flash hit ration on database level?
Cell flash cache read hits

Which disk group is used to keep OCR files on Exadata?
+DBFS_DG

How many Exadata wait events contained in 11.2.0.3 release?
There are 53 wait events are exadata specific events.

What is the difference between an Exadata X3-2 machine and an Exadata X3-8 machine?
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.

What are the three major components of Exadata database server?
Database Instance
ASM Instance
Database Resource Manager

What is the difference between DBRM and IORM?
DBRM is the feature of database while IORM is the feature of storage server software.

What are the different Exadata configurations?
The Exadata Appliance configuration comes as a Full Rack, Half Rack or Quarter Rack.
The Full Rack X2-2 has 6 CPU’s per node with Intel Xeon 5670 processors and a total of 8 Database Server nodes. These servers have 96GB of memory on each node. A total of 14 Storage server cells communicate with the storage and push the requested data from the storage to the compute nodes.
The Half Rack has exactly half the capacity. It has 6 CPU’s per node with core Intel Xeon 5670 processors and a total of 4 Database Server nodes. It has 96GB of memory per database server node with a total of 7 Storage server cells

What are the key Oracle Exadata Features?
Some of the key hardware and software features are:
1. Hardware level
2. Storage Server Cells
3. High Speed Infiniband Switch
4. Software level
5. Smart Scan,
6. Flash Cache
7. Hybrid Columnar Compression
8. IORM (I/O Resource Manager)

How much time required to apply bundle patch on Half rack Exadata Database Machine with rolling option?
Approximate 3 hours per Cell and DB server including Infiniband & PDU patching required 1 hour each.

What benefit we can get if we apply bundle patch on exadata in rolling fashion while ASM configured with high redundancy?
It will reduce the risk of storage disk failure

Advantages and disadvantages of rolling and non-rolling patching on Exadata Database Machine.?
Rolling
Advantages:
No downtime required
Disadvantages:
1. It takes more time to apply bundle patches
2. If ASM is on normal redundancy than disk failure on another Cell could lead to the DB corruption.

Non-Rolling
Advantages:
1. Less time required to do the patching
2. It could eliminate the risk of single disk failure if ASM configured with normal redundancy
Disadvantages:
Downtime required while applying bundle patch.

How to enable Flashcache compression?
CellCLI> ALTER CELL flashCacheCompress=true

How many Exadata Storage Server Nodes are included in Exadata Database Machine X4-8?
14 storage nodes

What types of operations does Exadata “offload”?
Some of the operations that are offloaded from the database host to the cell servers are:
Predicate filtering
Column project filtering
Join processing
Backups

What is cellcli?
This is the command line utility used to managed the cell storage.

How do you create obtain info on the Celldisks?
At the cellcli command line you can issue the “list celldisk” command.

How would you create a grid disk?
At the cellcli command you would need to issue the “create grididsk all ..” command.

What are the cellinit.ora and the cellip.ora files used for?
These files have the hostnames and the ip address of all the nodes in the cluster. They are used to run commands on remote database and cellserver nodes from a local host.

Example:
cat /etc/oracle/cell/network-config/cellinit.ora
ipaddress1=192.168.47.21/24

$ cat /etc/oracle/cell/network-config/cellip.ora
cell=”192.168.47.21:5042?
cell=”192.168.47.22:5042?
cell=”192.168.47.23:5042?

What operating systems does Exadata support?
Exadata has traditionally run Oracle Linux OS. Recently, Solaris has also been made available on this engineered system.

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

What is the difference between DBRM and IORM?
DBRM is the feature of database while IORM is the feature of storage server software.

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?

MOS 888828.1

Which tool is used to generate initial configuration files based on customer’s data?
OEDA (Oracle Exadata Deployment Assistance)

What is client or public network in exadata?
Client or public network is used to established connectivity between database and application.

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?
DBMS_COMPRESSION package

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.

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?
cell_offload_processing

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.

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

What Are The Key Oracle Exadata Features?
Some of the key hardware and software features are:
Hardware level
• Storage Server Cells.
• High Speed Infiniband Switch.
Software level
• Smart Scan.
• Flash Cache.
• Hybrid Columnar Compression.
• IORM (I/O Resource Manager).

Which ASM parameters are responsible for Auto disk management in Exadata?
_AUTO_MANAGE_MAX_ONLINE_TRIES --- It controls maximum number of attempts to make disk Online
_AUTO_MANAGE_EXADATA_DISKS --- It control auto disk management feature
_AUTO_MANAGE_NUM_TRIES    --- It controls maximum number of attempt to perform an automatic operation

How to enable Flashcache compression?
CellCLI> ALTER CELL flashCacheCompress=true

Which statistic can be used to check flash hit ration on database level?
Cell flash cache read hits

Which disk group is used to keep OCR files on Exadata?
+DBFS_DG

How many Exadata wait events contained in 11.2.0.3 release?
There are 53 wait events are exadata specific events.