Tips To Clear Oracle Exadata Certification Exam

Many DMA positions are available when you look for Oracle Exadata jobs, but it requires some skills to meet the job requirement. Credential of Oracle exadata certification is most appropriate for these position which can give confidence to the employer that you have a necessary skill to land for a job.


Oracle Exadata Certification is considered to be a one way ticket to a mouth-watering career in the field of Oracle Exadata Administrator, consultant and Implementer.

Today there are huge demand for Oracle Exadata Specialist in various industries. Also you can say DMA job is recession proof job in Oracle Database Technology.

Oracle offers two types of Exadata certifications. 

How To Deinstall OEM12c agent and Remove Its Targets from OMS repository?

Recently we have added target with wrong name hence it was required to deinstall OEM12c agent and associated targets from OMS repository.

Below steps would help you to perform this activity.


1. Deinstall agent from host/target

Export EM Agent HOme

$export EMAGENT_HOME=/u01/app/oracle/product/emagent/core/12.1.0.5.0

Deinstall Agent

$perl $EMAGENT_HOME/sysman/install/AgentDeinstall.pl -agentHome $EMAGENT_HOME

Why You Should Be Oracle Exadata Certified?

When you hear word Exadata , what first thing comes in your mind? Now the time comes for Exadata DMA rather than traditional DBA who can manage entire setup including network, storage, server, operating system, database, grid, asm etc...

To get this job you have to demonstrate your skill to the customer which is definitely 50% fulfilled if you are exadata certifiedIf you go to any Oracle customer who are on traditional oracle setup, all are thinking switch to the exadata machine because of many benefits for business as well operational.

How To Erase Data Securely On Exadata?

Give more attention who are looking to attend 1Z0-027 exam, you can expect 1-2 questions from this topic.

When disposing of an old hard drive, physically destroy the drive or completely erase all the data on the drive. Deleting the files or reformatting the drive removes only the address tables on the drive. 


The information can still be recovered from a drive after deleting files or reformatting the drive.

Monitoring Commands for Infiniband Switch


Infiniband is new for DBA so, DBA are not familiar with it in terms of management or monitoring but believe us monitoring or manage IB switches is not that much difficult.It's required just bit effort to understand how it works and how we can manage it. 

From Oracle Documentation you can learn it very well. Also it's not required much time to familiar with IB switches.

We can monitor IB switches using command line interface by executing simple linux commands for IB switches. 

Here we have give some of the commands which you can use for basic IB switch monitoring.

CELLSRVSTAT in Exadata Cell Storage

Cellsrvstat is very useful utility to get the cell level statastics for all the logical components of  cell like memory,io,smartio,flashcache etc...

Cellsrvstat is use to get quick cell level statistics from particular cell storage. Each CELL contains tool like cellsrvstat which gives brief information about CELL level statistics. It also helps you to get information of offloading and storage index.



It gives brief statistics for following sections.

io                  Input/Output related stats
mem              Memory related stats
exec               Execution related stats
net                 Network related stats
smartio           SmartIO related stats
flashcache       FlashCache related stats
ffi                   FFI related stats
lio                  LinuxBlockIO related stats

Simply running the utility from the command prompt, without any additional parameters or qualifiers, produces the output. You can also restrict the output of cellsrvstat by using the -stat_group parameter to specify which group, or groups, you want to monitor.

Help from cellsrvstat

[root@cell01 ~]# cellsrvstat -h

Oracle Exadata Interview Experience

Faisal is from UAE who recently appeared for the Exadata interview and successfully grab the opportunity to be an Exadata Consultant in one of the telecom company in UAE. He has shared his interview experience with us on mail which we are sharing here which will help you to get an idea of the interview questions which can be asked in the interview.


We are hearty thankful to Faisal who shared his feedback here. Your little effort will really guide other techies to boost the confidence while appearing into the interview for Exadata Database Machine. You can get the reference mail snap which is sent by Faisal HERE. We have trimmed his mail ID and full name for security purpose.

Below text we have taken from Faisal's mail which describes his interview experience.

Hello Sir,

Recently I have been appeared in exadata DBA interview for one of the telecom company in Dubai. There were three rounds of interview two F2F technical and one HR. I have cleared all three rounds of interview got selected for my dream job as Exadata Consultant. You guys helped me a lot to prepare for the interview, because of that only I have cleared it. Mostly all the exadata interview questions came from your ebook which was the best part for me as I have purchased it just before 10 days of first round. I dont' have enough words to thank you so thought to share what I have been asked in interview from technical front which can help 
you and others also. This will also help you to motivate yourself to keep continue what you are doing.

Administration Commands For COD


Let's continue from previous post of capacity of demand. Well, we will discuss that what all steps are required to increase CPU cores in Database Machine as a part of COD.

Step-1 Verify the number of active physical cores using the following command

DBMCLI> LIST DBSERVER attributes coreCount

Step-2 Use the following command to increase the number of active physical cores:

DBMCLI> ALTER DBSERVER pendingCoreCount = new_number_of_active_physical_cores

Step-3 Verify the pending number of active physical cores using the following command:

DBMCLI> LIST DBSERVER attributes pendingCoreCount

Step-4 Restart the server

Step-5 Verify the number of active physical cores using the following command:

DBMCLI> LIST DBSERVER attributes coreCount

The database server must be restarted after enabling additional cores. 

If the database servers are part of a cluster, then they can be enabled in a rolling fashion. 

Following table shows the Capacity On Demand core processor configuration for database machine.



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Capacity On Demand In Exadata Database Machine

Oracle has introduced capacity on demand on Exadata Database Machine so let's understand what is capacity on demand?

General Definition of COD:

Capacity on demand (COD) is a purchasing option that allows companies to receive equipment with more computer processing, storage, or other capacity than the company needs at the time of purchase, and have that extra capacity remain unused and unpaid for until the company actually requires it.

The number of active cores can be increased when additional capacity required is called capacity on demand.

Additional cores can be increased in 2-cores increment in X4-2 and X5-2 where as in X4-8 it can be increased in 8-cores increment.

Advantage:

Let's take an Example of database machine. When customer buy Exadata 1/8th Rack, only half of the cores would be enabled and half of them would be disabled so when customer's business expands and they required more computing power than they don't required to look around to increase it as vendor has already provided additional capacity which can be enabled at any time so in this case customer do not required to pass from purchasing procedure or any other hazardous which are time consuming. 

Simply they can enable it themselves whenever required.

What Is ASREXACHK Utility?



ASREXACHECK is the utility which is used to make sure that Exadata machine is communicating with ASR manager.


It checks the ASM configuration and performs the test from Database server and ILOM which sends mail from both to configured mail ID and it will report either succeeded or failure to send email.


The asrexacheck utility checks for known configuration issues as well as checking for any previous hardware faults that may not have been reported by ASR due a misconfiguration on the Exadata nodes.

When performing Preventive Maintenance on Exadata the Oracle will ask to run a PM Health Check script (asrexachk) on the individual systems to check the ASR configuration, as well as the health of the hardware components

Installation


How To Gather Exadata Statistics ?


Very quick note on gathering of Exadata statistics. 

Why?

Gathering Exadata specific system statistics ensure the optimizer is aware of Exadata scan speed.

Accurately accounting for the speed of scan operations will ensure the optimizer chooses an optimal execution plan in a Exadata environment. 

Following command gathers Exadata specific system statistics

SQL>exec dbms_stats.gather_system_stats(‘EXADATA’);


Risk:

Lack of Exadata specific stats can lead to less performance optimizer plans.


Action / Repair:

To see if Exadata specific optimizer stats have been gathered, run the following query on a system with at least 11.2.0.2 BP18 or 11.2.0.2 BP8 Oracle software. 

Exadata Patching - Compute Node

In earlier posts we have seen how to patch infiniband switch and Cell Server. 

Well, now let's continue with Database Server patching which is pending since long time.


Patching on Database server can be performed serially or in parallel using DCLI utility.

dbnodeupdate.sh utility is used to perform the database server patching


What dbnodeupdate.sh utility does?

  • Stop/unlock/disable CRS for host restart
  • Perform LVM snapshot backup of / filesystem
  • Mount yum ISO image and configure yum
  • Apply OS updates via yum
  • Relink all Oracle homes for RDS protocol
  • Lock GI home and enable CRS upon host restart


Patching:

Exadata Cell Services Administration




There are multiple services runs on Exadata cell server which need to administer on multiple occasion. i.e maintenance, upgrade, monitoring. Here we have listed down the commands to manage each cell service.




  • Check the status of all CELL services

#service celld status

           OR

#cellcli -e list cell attributes rsStatus, msStatus, cellsrvStatus detail

  • Start all CELL services

#service celld start

          OR

#cellcli -e alter cell startup services all

  • Stop all CELL services

How To Install Telnet On Exadata?

Telnet is not pre-configured on DB server or Cell server in Exadata Machine. If we required than we can install it separately using Linux rpm.

Telnet is used to check whether particular port is open or not. You can follow below steps to install telnet utility on Database machine.


Step 1: Download required telnet rpm from Linux rpm repository 

RPM : telnet-0.17-39.el5.x86_64.rpm  
RPM Repository URL :  http://public-yum.oracle.com/repo

Note: RPM version can be different as per OS

Step 2: Move rpm to database server

Step 3: Install rpm

[root@db01 ~]# rpm -ivh telnet-0.17-39.el5.x86_64.rpm
Preparing...  ################################### [100%]
   1:telnet    ################################### [100%]

Step 4: Test the telnet utility 

[root@db01 ~]# telnet db02 1521
Trying 192.168.10.12...
Connected to db01.
Escape character is '^]'.

Golden Gate Checkpoint Table Error: Could not Delete DB Checkpoint for REPLICAT

Recently while we were working on goldengate configuration on Exadata we faced below error while deleting the replicate process. Hope it will help you.

ERROR


GGSCI (dm01) 4> delete replicat EXREP1

ERROR: Could not delete DB checkpoint for REPLICAT EXREP1 (OCI Error ORA-00942: table or view does not exist (status = 942). Deleting from checkpoint table ogg.checkpointtable, group 'EXREP1', key 3261899073 (0xc26ca141), SQL <DELETE FROM ogg.checkpointtable  WHERE group_name = 'EXREP1' AND     group_key  = 3261899073>).

After getting above error we have checked whether EXREP1 has been deleted or not, but because of above error it has not been deleted.


GGSCI (dm01) 6> info all


Program     Status      Group       Lag at Chkpt  Time Since Chkpt

MANAGER     RUNNING
REPLICAT     STOPPED     EXREP1     00:00:00      00:00:01


Solution

While deleting specify ! argument as well to remove replicat process.


GGSCI (dm01) 5>  delete replicat EXREP1 !

WARNING: Could not delete DB checkpoint for REPLICAT EXREP1 (OCI Error ORA-00942: table or view does not exist (status = 942). Deleting from checkpoint table ogg.checkpointtable, group 'EXREP1', key 3261899073 (0xc26ca141),SQL <DELETE FROM ogg.checkpointtable  WHERE group_name = 'EXREP1' AND        group_key  = 3261899073>).

Now you can seen in info all, EXREP1 process has been deleted successfully.

GGSCI (dm01) 6> info all


Program     Status      Group       Lag at Chkpt  Time Since Chkpt

MANAGER     RUNNING


What is DBMCLI in Exadata?



Definition:

Starting Exadata Storage Server Release 12.1.2.1.0 a new command-line interface called DBMCLI is introduced for database server.



DBMCLI is the database machine command line interface to administrate exadata database server.

It runs on each database machine. By default it is pre-installed on each database server and on virtualized machine while it shipped.

DBMCLI utility is included in latest release 12.1.2.1.0 of Exadata image


Using DBMCLI:

  • Configure ASR, capacity-on-demand, infrastructure as a service
  • Configure database server e-mail alerts
  • Configure, manage and monitor database servers
  • Start stop server
  • Manage server configuration information
  • Enable or disable the server
  • It can be start through SSH by executing DBMCLI command
  • Used to monitor database server metrcis
  • It uses DB server OS authentication, it doesn't required login parameter, moreover like CELLCLI

Syntax:

  
$dbmcli [port_number] [-n] [-m] [-xml] [-v | -vv | -vvv] [-x] [-e command]

Here 

Port_number  - Specifies HTTP port number of database server. If not specified it will use the port from cellinit.ora file.If it is not in cellinit.ora than port number 8888 will be used.

n                 - Execute DBMCLI command in non-interactive mode
m                - Run DBMLI in run monitor mode (Read Only)
xml              - Display output in xml format, can be used for OEM
v, vv, vvv      - Set log level, Fine, Finer and Finest level of log
x                 - Suppress the banner
e                 - To execute specific DBMCLI command 

Users:

DBMCLI has two users

dbmadmin   - Used for administration purpose
dbmmonitor - Used for monitoring purpose

You can follow our Exadata Certification Question Bank to achieve maximum success in your Exadata certification.

Exadata Patching - Cell Server

Cell storage patching can be done by patchmgr utility which is used to do a patching in rolling as well in non-rolling fashion.


Syntax: ./patchmgr -cells cell_group -patch [-rolling] [-ignore_alerts] [- smtp_from "addr" -smtp_to "addr1 addr2 addr3 ..."]


Here addr is the sending mail id which is used to send status of patching and addr1,addr2,addr3 are receiving mail id to receive the status of patching.

Step-1  First note down the current image version of cell by executing 

#imageinfo

Step-2  Go to cell patch directory where patch has been copied

/19625719/Infrastructure/11.2.3.3.1/ExadataStorageServer_InfiniBandSwitch/patch_11.2.3.3.1.140708

Step-3  Reset the server to a known state using the following command

./patchmgr -cells cell_group -reset_force


Step-4  Clean up any previous patchmgr utility runs using the following command

./patchmgr -cells cell_group -cleanup


Step-5 Verify that the cells meet prerequisite checks using the following command

Exadata Patching - Infiniband Switch


Here we have listed down bullet points to patch IB switches on Exadata Database Machine.



Syntax: #patchmgr -ibswitches [ibswitch_list_file] <-upgrade | -downgrade [-ibswitch_precheck] [-force]]

Here 

ibswitch_list_file contains IP of all the IB switches
Upgrade - to upgrade the switch
Downgrade - to downgrade the switch
ibswitch_precheck - to check the prerequisites

Patchmgr utility would be available in storage server patch directory.

Patching

#./patchmgr -ibswitches ibswitches -upgrade -ibswitch_precheck


How it works?
  • Disable Subnet Manager
  • Copy firmware to switch
  • Check minimal firmware version to upgrade it
  • Verify enough space in /tmp and /
  • Verify for free memory to start upgrade
  • Verify host details in /etc/hosts and /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth1
  • Verify for NTP server
  • Pre-upgrade validation
  • Start upgrade
  • Load firmware
  • Disable Subnet Manager
  • Verify that /conf/configvalid is set to 1
  • Set SMPriority to 5
  • Reboot switch
  • Restart Subnet Manager 
  • Start post-update validation
  • Confirmation: Inifiniband switch is at target patching level
  • Verifying host details in /etc/hosts and /etc/sysconfig/network-scripts/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth1
  • Verifying NTP Server
  • Firmware verification on InfiniBand switch 
  • Post-check validation on IBSwitch 
  • Final Confirmation: Update switch to 2.1.3_4 (Firmware version)

Once it completes on one switch, it will start to upgrade next available switch and in last it will give overall status of upgrade.

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How To Customize Shell Prompt To Database SID ?

Typically shell has its own default prompt with $ sign when you logged into the Linux server using Oracle user. 

Question might be come that why we should change it. 

Well, If there are multiple databases configured on the server than customizing prompt will help us to identify session where we are working at a time. 

This will help to eliminate human error by accidentally running particular command on wrong database or session.


Following are the steps to customize your default prompt to Database SID.

Default Prompt:

[oracle@db01 ~]$ 


Change it to Oracle SID

Step 1 First check the value of $PS1 prompt by executing below command

It will give below values 

[oracle@db01 ~]$ echo $PS1
[\u@\h \W]\$

PS1 (Prompt String 1) is one of the prompts available in Unix

Step 2 Export Oracle SID:

$export ORACLE_SID=test

Step 3 Now export PS1 with ORACLE_SID 

$export PS1=[$ORACLE_SID]

Step 4 After executing above command you will get the prompt like below

[oracle@db01 ~]$ export PS1=[$ORACLE_SID]
[test]
[test]
[test]pwd
/home/oracle

You would also like below examples for customization of prompt.


How To Calculate Network Bandwidth On Exadata Database Servers?

Let's get understanding to calculate bandwidth between Database servers on Exadata. Exadata available for both 10Gig and 1Gig network configuration.

Here we have given example for 1Gig network configuration. Same methodology can be used for other network configuration.

There are multiple tools to calculate network bandwidth between two points.

Like, Iperf, NDT, NC, PCATTCP etc...

Here we will use NC utility to calculate bandwidth.

We have two database node on exadata 

DB01
DB02

Step 1 Download nc-1.84-10.fc6.x86_64.rpm and copy on the nodes where you want to carry out the bandwidth test.

You can get this rpm from HERE 

Step 2 Install RPM on both nodes.

[root@db01 ~]# rpm -ivh nc-1.84-10.fc6.x86_64.rpm
Preparing...      ################################# [100%]
   1:nc             ################################# [100%]

[root@db02 ~]# rpm -ivh nc-1.84-10.fc6.x86_64.rpm
Preparing...    ################################## [100%]
   1:nc           ################################## [100%]
   
Step 3 Using NC utility start receiver on free port. Make sure port which you are using is not utilized. Here we have used 9999 port.


What Should Be The Order of Exadata Machine Patching?

In earlier post we have given overview for downloading and extract patch on database system.

Now lets have an overview of patching order for Oracle Exadata Machine with list of utility which need to be used to apply it, as it is not compulsory to maintain this order but usually we should follow it to mitigate risk.

We have give the patch location of particular component based on patch number 19625719 (QFSDP).

---------------------------------------------------------------------------------------------
1. InfiniBand Switch 
  • It will be available with storage server patches
  • First apply it on spine switch than leaf switches

Exadata Patching - Download, Extract, Prepare

Let's go through the Exadata machine patching procedure in bullet points based on our patching experience.

Initially planned to write a article for entire patching activity for all database machine components in single post but it will look bit nasty so thought to write a post for each database machine component separately which would be easy to understand.

Exadata patching activity is very easy task if you plan it well.

Well, let's start from downloading the bundle patch and extract it to compute node. 

1. First go to the Oracle Document ID 888828.1, this is the first read requirement for any exadata database machine patching activity.

Oracle Exadata Interview Questions and Answers eBook


Are you trying to wow interviewers, but aren't able to? Does the thought of being interviewed send you into a tizzy? 

Well look no further, because this book will help you wow the interviewers and help you get the job as Database Machine Administrator.

If you go for raw materials, it would take hundreds of hours to prepare it which you will find here thorough research well-presented and much shorter road to clear your Exadata interview.

Even if you have experience with Oracle Exadata, this guide will help you assess your current skill level and brush up on any new improvements that might test you during the job interview.

                                Get Sample Copy of eBook Free

The study guide consists of 370+ topic wise questions and answers. You can also utilize this book in your day to day job. We all have spent countless hours to prepare  and make it simple and effective. 

It is not only interview questions but you can review whole Exadata architecture quickly by reviewing this book which helps you to extend your Oracle Database skill set to the fast-growing Exadata platform.

Rather than going through comprehensive, textbook-sized reference guides, this book includes only the information required immediately for job search to build a career as an Oracle Exadata Professional.

We are confident that more than 95% interview questions about Exadata Machine will be covered from this book. 

Get this book to stay miles ahead of your competition! 

7 Things You Should Know About Exadata X5-2



Following are the major differences or features of Exadata Machine X5-2 compare to X4-2 machine.






  • Solaris operating system is not supported on ED X5 anymore
  • ED X5 supports OVM 
  • High performance configuration has been replaced by Extreme Flash
  • Each extreme flash storage contains 8 x 1.6 TB PCI flash drives
  • Disk controller battery eliminated for flash card
  • CPU increased to 288 cores per full rack, 2 x 18 core per Database server
  • Memory can be upgraded up to 768 GB per database server

How to use compression advisor on Exadata?

Compression advisor is used to estimate compression ratio of a particular table by executing compression advisor utility.

Benefits:
It can be used to estimate compression ratio of object/table , based on that we can go for the best possible compression method i.e. OLTP, Query Low, Query High, Archive Low and Archive High.


It also helps us to decide whether we will get optimal benefit of compression or not.

We can come to know how much storage free space we would get if we compress the tables which helps us to do better capacity planning for future requirement.

Following are the steps which need to performed to get the compression ratio of any object.


Exadata Document Available Publicly

Its great news to all Oracle techies. Now Oracle Exadata Document is available publicly on Oracle website. No need Oracle support id to view the document.

You can get it from below link.

                                         Oracle Exadata Documentation


How to configure Exadata cell alert notification?



We can configure SMTP alert on cell level using cellcli utility on each cell to get alert notification by providing below required details.




CellCLI> ALTER CELL smtpServer='mailserver.example.com',
             smtpFromAddr='exadataalert@example.com',
             smtpFrom='Exadata Alert',         
             smtpToAddr='exaadtadba@example.com',
             notificationPolicy='maintenance,clear,warning,critical',
             notificationMethod='mail,snmp'

Here,

smtpserver - Mail Server Name
smtpFromAddr - Mail id from where alert will be send to 
smtpToAddr - Mail id on which alert should go
notificationPolicy - Define notification policy
notificationMethod - method of notification


Validate email notification on cell by executing

CellCLI> ALTER CELL VALIDATE MAIL

We can also change the format of E-mail address by executing commands like

CellCLI> ALTER CELL emailFormat='text'
CellCLI> ALTER CELL emailFormat='html'

                                How to calculate IOPS in Exadata ?

GoldenGate - libnnz11.so: cannot open shared object file

While login into Goldengate command line interface we faced below error. Resolution or error is not that much complicated but many time we are not able to find out what can be the issue while working in under pressure situation so thought to write this piece.

[oracle@ggtest ogg]$ ./ggsci
./ggsci: error while loading shared libraries: libclntsh.so.11.1: cannot open shared object file: No such file or directory

Only need to export library from oracle home to resolve this error. It is better to append this in .bash_profile of Oracle user.

[oracle@ggtest ogg]$ export LD_LIBRARY_PATH=$ORACLE_HOME/lib
[oracle@ggtest ogg]$ ./ggsci

Oracle GoldenGate Command Interpreter for Oracle
Version 11.2.1.0.1 OGGCORE_11.2.1.0.1_PLATFORMS_120423.0230_FBO
Linux, x64, 64bit (optimized), Oracle 11g on Apr 23 2012 08:32:14

Copyright (C) 1995, 2012, Oracle and/or its affiliates. All rights reserved.

GGSCI>

Comparison between Exadata X4-2 and X5-2

Obliviously ED X5 would be faster and flexible compare to earlier version of ED. Here we have given comparison between X5 and X4 full configuration ED rack based on datasheet provided by Oracle.



Now from X5-2 Oracle introduced Oracle Virtual Machine to do the virtualization on ED machine, if there is any requirement of hard limits on CPUs and memory or required independent OS/Admin than we can use this virtualization feature.

There is no licence cost for OVM , it's free of cost with ED X5-2.

From ED X5-2 High performance disk has been replaced with Extream Flash (EF).