What are Patches and how to apply patches ?

Patching  is one  of  the  most  common  task  performed  by  DBA's  in  day-to-day  life  . Here , we  will discuss  about  the various  types  of  patches  which  are  provided  by  Oracle  . Oracle  issues  product fixes  for  its  software called  patches. When  we  apply  the  patch  to  our  Oracle  software installation, it updates  the  executable  files, libraries,  and  object  files in  the software  home directory . The patch application  can  also  update  configuration  files and  Oracle-supplied  SQL schemas . Patches  are  applied by  using  OPatch, a utility supplied by Oracle , OUI  or  Enterprise Manager Grid Control . 

Oracle Patches are of various kinds . Here , we are broadly categorizing  it  into  two groups .

1.) Patchset  : 
2.) Patchset Updates : 

1.) Patchset  :  A group of  patches  form  a  patch  set. Patchsets  are  applied  by  invoking OUI (Oracle Universal Installer) . Patchsets  are  generally  applied  for  Upgradation  purpose . This  results  in  a version change  for our  Oracle  software, for  example,  from  Oracle Database 11.2.0.1.0  to  Oracle  Database 11.2.0.3.0.  We will cover this issue later .

2.) Patchset Updates : Patch Set Updates  are  proactive cumulative patches containing  recommended bug fixes that are released on a regular and predictable schedule .  Oracle has catergaries as :

i.) Critical Patch Update (CPU)  now refers  to  the  overall  release of security  fixes each  quarter  rather than the cumulative database security  patch  for  the quarter.  Think  of  the  CPU as  the  overarching quarterly release and not as a single patch .

ii.) Patch Set Updates (PSU)  are  the same cumulative patches  that  include  both  the  security  fixes and priority  fixes.  The key with  PSUs  is  they are  minor version  upgrades   (e.g., 11.2.0.1.1  to  11.2.0.1.2). Once a  PSU  is  applied, only  PSUs  can  be  applied  in  future  quarters  until  the database  is  upgraded to a new base version. 

iii.) Security Patch Update (SPU)  terminology  is  introduced  in  the October 2012 Critical Patch Update as  the  term  for the quarterly security patch.  SPU  patches are the same  as  previous  CPU  patches,  just a new  name .  For  the database, SPUs  can  not  be  applied  once  PSUs  have  been  applied  until  the database is  upgraded  to a  new base version.

iv.) Bundle Patches  are the quarterly patches for Windows  and  Exadata  which  include  both the quarterly security patches as well as recommended fixes. 

PSUs(PatchSet Updates) or CPUs(Critical Patch Updates) ,SPU are applied via opatch utility.

How to get Oracle Patches :

We  obtain  patches  and  patch  sets  from  My Oracle Support (MOS) . The  ability  to  download a specific  patch  is  based  on  the contracts associated  to  the support  identifiers  in  our  My Oracle Support  account.  All  MOS  users  are  able  to  search  for  and  view all  patches,  but  we  will  be prevented  from  downloading  certain types  of  patches  based  on  our  contracts.

While   applying   Patchset or  patchset upgrades , basically there are two entities in the Oracle Database environment 

i. )  Oracle Database Software
ii.)  Oracle Database

Most of the database patching activities involve, in the following sequence

•  Update  "Oracle Database Software"  using   './runInstaller'  or   'opatch apply'   known  as "Installation"  Tasks.
• Update  "Oracle Database"  (catupgrd.sql  or  catbundle.sql ...etc)  to  make  it  compatible  for  newly  patched  "Oracle database Software"   known  as  "Post Installation"  tasks. 

Patchset  OR  CPU/PSU  (or one-off)  patch  contains  Post  Installation  tasks  to  be  executed  on  all Oracle  Database  instances  after  completing  the Installation  tasks. If  we  are  planning  to  apply  a patchset  along  with  required  one-off-patches (either CPU or PSU or any other one-off patch),  then  we can  complete  the  Installation  tasks  of  the   Patchset+CPU/PSU/one-off  patches at once and then execute  Post  Installation  tasks of  the  Patchset+CPU/PSU/one-off  patches  in  the  same sequence as they were  installed . 

This  approach  minimizes  the  requirement  of  database  shutdown  across  each  patching  activity and simplifies  the  patching  mechanism as two tasks: 

• Software update and then
• Database update.

Here , we  will  cover  the  Opatch Utility in details along with example. 

OPatch  is  the  recommended (Oracle-supplied)  tool  that  customers  are  supposed  to  use  in  order to apply  or  rollback  patches. OPatch  is  PLATFORM  specific . Release is based on Oracle Universal Installer version .   OPatch  resides in  $ORACLE_HOME/OPatch .  OPatch  supports  the  following :

• Applying  an  interim  patch.
• Rolling  back  the  application  of  an  interim  patch.
• Detecting  conflict  when  applying  an  interim  patch  after  previous  interim  patches  have  been applied.  It  also  suggests  the  best  options  to  resolve a conflict .
• Reporting on installed products and interim patch.

The  patch  metadata  exist in  the  inventory.xml  and  action.xml  files  exists under <stage_area>/<patch_id>/etc/config/   

Inventory  .xml  file  have  the  following  information :

• Bug number 
• Unique Patch ID
• Date of  patch year  
• Required and Optional components 
• OS platforms ID 
• Instance shutdown is required or not 
• Patch can be applied online or not 

Actions   .xml  file  have  the  following  information .

• File name and it location to which it need to be copied 
• Components need to be re-linked 
• Information about the optional and required components

Here are steps for applying  patches on linux Platform : 

1.) Download the required Patches from  My Oracle Support (MOS) : 

• Login to metalink.
• Click "Patches & Updates" link on top menu.
• On the patch search section enter patch number and select the platform of your database.
• Click search.
• On the search results page, download the zip file.

2.)  Opatch version  :
Oracle  recommends  that  we  use  the  latest  released  OPatch , which  is  available  for  download  from My  Oracle  Support .  OPatch  is compatible  only  with  the version  of  Oracle  Universal  Installer  that  is installed  in  the  Oracle  home. We  can  get  all  Opatch  command  by  using  Opatch  help  command .

3.) Stop all the Oracle services  :
Before applying Optach , make sure all the Oracle services are down . If they are not down then stop/down the oracle related Services . Let's crosscheck it 

$ ps -ef |grep pmon
oracle   15871 15484  0 11:20 pts/2    00:00:00 grep pmon

$ ps -ef |grep tns
oracle   15874 15484  0 11:20 pts/2    00:00:00 grep tns

4.) Take Cold Backup :  

It  is  highly  recommended  to backup  the software  directory  which  we  are  patching  before  performing any  patch  operation . This  applies  to  Oracle  Database  or Oracle  Grid  Infrastructure  software installation  directories.  Take the backup of following 

• Take the Oracle software directory backup 

$ tar -zcvf   /u01/app/oracle/product/11.2.0/ohsw-bkp-b4-ptch.tar.gz   /u01/app/oracle/product/11.2.0   

• Take  backup of oracle database . 

$ tar  -zcvf    /u01/app/oracle/oradata/dbfl-b4-ptch.tar.gz     /u01/app/oracle/oradata     
Here all the database files are in oradata  directory .

• Take backup of OraInventary

$ tar  -zcvf   /u01/app/oraInventary/orinv-b4-ptch.tar.gz     /u01/app/oraInventary  


5.)  Apply  OPatches 
Set  our current directory to the directory where the patch is located and then run the OPatch utility by entering the following commands:

$ export  PATH=$ORACLE_HOME/OPatch:$PATH:
$ opatch apply .

6.)  Post Installation : 

Once , the  Opatch  installation  completed  successfully . Perform  the  post  Installation steps . Startup  the oracle  database  with  new  patched  software and  run catbundle.sql  scripts  which  is  found  in           $ORACLE_HOME/rdbms/admin   directory .

The catbundle.sql execution is reflected in the dba_registry_history view by a row associated with bundle series PSU.


7.) Finally check the status of patch status : 
We can check the final status of applied patched new Oracle Home by using the below command .
SQL > select  *   from  dba_registry_history   order  by  action_time  desc ;


Notes :
i.) If  we are using  a  Data Guard Physical Standby database, we  must  install  this  patch  on  both  the primary  database and  the physical  standby database .

ii.)  While applying patching take care of  mount point status .There should be sufficient Space .


There are few good demo on Optach . Check the below link 
Click Here
Click Here

For More About Opatch : Click Here


Enjoy   :-)   :-) 

Oracle Database 12C Release 1 Installation on Linux

Oracle 12c (Oracle 12.1.0.1) has been released and is available for download . Oracle 12C Installation steps are almost  same as  that  of   Oracle 10g and 11g Installations  . Oracle  12c  is  available  for  64 bit . Here , we will see step-by-step Installation of Oracle 12C database .  

Step  1 :  Oracle S/W Installation
We can download Oracle 12c  s/w from e-delivery or from OTN .  Below are Link

http://www.oracle.com/technetwork/database/enterprise-edition/downloads/index.html
https://edelivery.oracle.com/EPD/Download/get_form?egroup_aru_number=16496132


Step 2 :  Hardware Requirements 
Oracle Recommand the following requirement for installation .
RAM     =  2GB of RAM or more
Swap    = 1.5 times of RAM if RAM less than 2 GB , equal to size of RAM is RAm size is more than 2GB
Disk Space      = More than 6.4 GB for Enetrprise Edition .
Tmp directory  =  Minimum 1GB of  free space


Step 3 :  Hardware Verifications 
[root@server1 ~]# grep  MemTotal   /proc/meminfo
MemTotal:      3017140 kB

[root@server1 ~]# grep  SwapTotal   /proc/meminfo
SwapTotal:     4105420 kB

[root@server1 ~]# df  -h  /tmp
Filesystem            Size    Used     Avail     Use%     Mounted on
/dev/sda1              46G   19G      25G       44%          /

[root@server1 ~]# df  -h 
Filesystem            Size       Used     Avail      Use%      Mounted on
/dev/sda1              46G      19G       25G       44%          /
tmpfs                    1.5G       0          1.5G       0%           /dev/shm
/dev/hdc              3.4G       3.4G        0        100%         /media/RHEL_5.3 x86_64 DVD

[root@server1 ~]#  free
                  total           used           free           shared    buffers     cached
Mem:       3017140     715376    2301764          0       109776     384096
-/+ buffers/cache:        221504    2795636
Swap:      4105420          0         4105420

[root@server1 ~]# uname  -m 
x86_64

[root@server1 ~]# uname  -a 

Linux   server1.example.com      2.6.18-128.el5 #1    SMP    Wed    Dec 17 11:41:38 EST   2008    x86                                                                                        

_64 x86_64 x86_64      GNU/Linux

Step 4 :  Packages Verifications 

The  following  packages  are  required  for  the  Oracle  Installation , so  make  sure  all  the  packages are installed .

make-3.81
binutils-2.17.50
gcc-4.1.2                       (x86_64)
gcc-c++-4.1.2               (x86_64)
compat-libcap1              (x86_64)
compat-libstdc++-33     (x86_64)
glibc-2.5-58                   (x86_64)
glibc-devel-2.5               (x86_64)
libgcc-4.1.2                    (x86_64) 
libstdc++-4.1.2               (x86_64)  
libstdc++-devel-4            (x86_64)  
libaio-0.3.106                  (x86_64)
libaio-devel-0.3               (x86_64) 
ksh 
sysstat  
unixODBC  
unixODBC-devel

Execute  the  below command  as  root  to  make  sure  that  we  have  all  this  rpms  installed. If  not installed,  then  download  them   from  appropriate  linux  site or  we will  find  the  package from  the Red Hat Enterprise Linux 5 DVD . For example , 

# rpm  -qa  | grep  glib* 

The  above  command  will  display  all  the  installed  packages,  name  starting  with   glib,  similarly  we  can  check  for  all  others  packages . If  any of  the  above  packages  are  not  installed, run  the  following command:

# rpm  -ivh  </path/to/><version>.i386.rpm

Steps 5  :  Kernel Parameters
Add the below kernel Parameters in the  /etc/sysctl.conf  file

fs.file-max = 6815744
kernel.sem = 250 32000 100 128
kernel.shmmni = 4096
kernel.shmall = 1073741824
kernel.shmmax = 2147483648
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048576
fs.aio-max-nr = 1048576
net.ipv4.ip_local_port_range = 9000 65500

After  adding these  lines  to  /etc/sysctl.conf , run  the  below command  as  root  to  make  them  enabled.

 #  sysctl   -p 


Step 6 :  Edit the /etc/security/limits.conf file

To  improve the  performance  of   the  software  on  Linux  systems, we  must  increase  the  following  shell limits   for  the  oracle  user . Add  the  following  lines  to the  /etc/security/limits.conf  file :

oracle    soft  nproc  2047
oracle    hard  nproc  16384
oracle    soft  nofile  1024
oracle    hard  nofile  65536

Where  "nproc"  is  the maximum  number  of  processes  available to  the  user  and  "nofiles"  is  the  number  of  open  file  descriptors.

Step 7  :  Create User and Groups 

Starting  with  Oracle  Database  12c , we  can  create  new  administrative  privileges  that  are  more  task-specific  and  less  privileged  than  the  OSDBA/SYSDBA  system privileges  to support specific administrative  privileges  tasks  required  for  everyday  database  operation. Users  granted  these  system privileges  are  also  authenticated  through operating system group membership .

We  do  not  have to  create  these  specific  group  names, but  during  installation we  are  prompted  to provide  operating  system  groups  whose  members  are  granted  access  to  these  system  privileges.  we  can  assign  the same  group  to  provide  authentication  for  these  privileges, but  Oracle  recommends  that we  should  provide  a  unique  group  to  designate each  privileges.

i .) The OSDBA group (typically, dba)  :  This group identifies operating system user accounts that have database administrative privileges (the SYSDBA privilege).

#groupadd  -g  501  dba  

ii .) The Oracle Inventory Group (oinstall) :  This group owns the Oracle inventory that is a catalog of all Oracle software installed on the system. A single Oracle  Inventory group is required for all installations of Oracle software on the system.

# groupadd  -g  502  oinstall  

iii .) The OSOPER group for Oracle Database (typically, oper)  :  This  is an optional  group. We  create  this  group  if  we  want  a separate  group of  operating  system  users  to  have a  limited  set  of database  administrative  privileges  for  starting  up  and shutting  down the  database  (the SYSOPER privilege). 

# groupadd  -g  503  oper  

iv .) The OSBACKUPDBA group for Oracle Database (typically, backupdba)  :   Create this group if we  want a  separate  group of  operating  system  users  to  have a  limited  set  of database backup and recovery related administrative privileges (the SYSBACKUP privilege).
# groupadd   -g   504   backupdba 

v .) The OSDGDBA group for Oracle Data Guard (typically, dgdba)  :   Create  this  group  if  we want  a  separate  group of  operating  sytsem  users to  have a  limited  set of   privileges  to  administer  and monitor  Oracle Data Guard  (the SYSDG privilege).

# groupadd   -g   505   dgdba 

vi .) The OSKMDBA group for encyption key management (typically, kmdba)   :  Create  this  group if  we  want  a  separate group  of  operating  sytem  users  to have a  limited  set  of  privileges  for encryption  key  management  such  as Oracle  Wallet  Manager  management  (the SYSKM privilege).

#  groupadd   -g   506   kmdba  

vii .) The OSDBA group for Oracle ASM (typically, asmdba) :   The  OSDBA  group  for  Oracle ASM can  be  the  same group u sed as  the OSDBA  group  for  the database, or we  can  create a separate OSDBA group for Oracle ASM to provide administrative access to Oracle ASM instances .

# groupadd  -g  507   asmdba 

viii .) The OSASM group for Oracle ASM Administration (typically, asmadmin)  :  Create  this  group as  a  separate group if  we  want  to  have  separate  administration  privileges  groups  for  Oracle  ASM and Oracle  Database  administrators. Members  of  this  group  are  granted  the  SYSASM  system privileges  to  administer  Oracle ASM  .

#  groupadd  -g   508   asmoper

ix .)  The OSOPER group for Oracle ASM (typically, asmoper)  :   This is an optional group. Create this group  if  we  want  a separate  group of  operating  system  users  to  have  a limited  set  of  Oracle instance  administrative  privileges  (the SYSOPER for ASM privilege),  including starting up and stopping the  Oracle  ASM  instance . By default ,  members of  the OSASM group  also  have all privileges granted by the SYSOPER for ASM  privilege.

# groupadd   -g   509  asmadmin 

x . ) Create Oracle user  :
# useradd -u 54321 -g oinstall -G dba,asmdba,backupdba,dgdba,kmdba  oracle
#passwd oracle
<<ORACLE PASSWORD >>

The  -u  option  specifies  the  user  ID. Using  this  command  flag  is optional  because the system can provide  with  an  automatically  generated  user  ID  number. However,  Oracle  recommends  that  we should specify a number. We must note the user ID number because we need it during preinstallation.

Step 8 :  Creating oracle directories 

As  per  OFA, oracle base directory has  the  path  :  /mount_point/app/oracle_sw_owner  where mount_point   is  the mount  point directory  for  the  file system  that  will  contain  the  Oracle software . I have  used  /u01  for  the mount point  directory. However, we  could  choose  another  mount point directory,  such  as  /oracle or /opt/soft.

# mkdir -p /u01/oracle/product/12.1.0/db_1
# chown -R oracle:oinstall /u01
# chmod -R 777 /u01


Step 9 :  Setting Oracle Enviroment 
Edit  the  /home/oracle/.bash_profile  file and  add  following  lines:
# su - oracle
$ vi  .bash_profile
export TMP=/tmp
export TMPDIR=$TMP
export ORACLE_BASE=/u01/oracle
export ORACLE_HOME=$ORACLE_BASE/product/12.1.0/db_1
export PATH=/usr/sbin:$PATH
export PATH=$ORACLE_HOME/bin:$PATH
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:/lib:/usr/lib
export CLASSPATH=$ORACLE_HOME/jlib:$ORACLE_HOME/rdbms/jlib


Step 10  :   Check firewall and Selinux  
Make sure Selinux be either disable or permissive . Check "/etc/selinux/config" file and make following changes .
SELINUX=permissive
Once ,Selinux value is set than restart the server or or run the below command
# setenforce Permissive

If  Firewall is enabled ,we need to disable it . we can disable by using below command
# service iptables stop
# chkconfig iptables off


Step 11 :  Finally run the runInstaller for Installation of  Oracle 12c release 1

















Once ,  runInstaller get initaited , OUI get invoked and rest are interative graphical console .

Click next and proceed forward .

Click  on "Yes"  button and proceed .

Select "Skip Software Updates" option and click on next button .

Select  "Create and configure a database" option and click on next button

Here , I selected the "Desktop Class" option . Click on next button

Enter the Administrative Password and click next

Click on "Yes" option and proceed forward

Click on next button

Make sure all the prerequisite must be successfull and passed  .
 

Summary page displays all the locations and database information . Click next

Oracle Database Installation in process

Execute the configurations scripts from root

Run the scripts from root .

Oracle Database in process

Database creation in process .

Database creation in process .

Database Creation complted .

Installation of Oracle database was successfull .

Finally connected  with Oracle 12c database .


Enjoy   :-)  :-)  :-) 

Oracle Database 12c Available for Download

Finally, Oracle has released the most awaited oracle Database i.e, 12c (Oracle 12.1.0.1) . It  is available for download from the Oracle Software Cloud (formerly know as eDelivery) and  OTN (Oracle Tech Network) for 64bit linux and solaris  . Oracle 12c is not available for 32 bit .  Oracle has yet not released the AIX and Window database 12c s/w, hopefully will release soon . Here are links for download Oracle s/w. 

eDelivery          : Click here  to download from eDelivery .
OTN                  : Click here  to download from OTN .
Documentation : Click here  to download  document of 12c

There are some very exiting features in Oracle 12c Database .One of them is "Pluggable Database " which allows a  single Oracle database  instance to  hold  many other databases, allowing  for  more efficient  use of  system resources and easier management. I will be soon download and post about this features .

An official Oracle price list, which was updated Tuesday, showed a "multitenant" database option priced at $17,500 per processor. A processor license for the main  Enterprise  Edition  remained  priced at $47,500 per processor.


Enjoy    :-) 

ORA-00020 and Impact on database on increasing processes values

The maximum number of processes is specified by the initialization parameter "processes" . When this maximum number of process is reached, no more requests will be processed. If we are try to connect with database then we get the below errors . 

Here for testing purpose, i have set  my processes value to 30 for this demo .

[oracle@server1 ~]$ sqlplus "sys/xxx as sysdba"
SQL*Plus: Release 11.2.0.1.0 Production on Fri May 24 13:36:53 2013
Copyright (c) 1982, 2009, Oracle.  All rights reserved.
ERROR:
ORA-00020: maximum number of processes (30) exceeded

I usually check my alert logfile for any oracle errors  and find following info .

Alert logfile
Fri May 24 13:38:30 2013
ORA-00020: No more process state objects available
ORA-20 errors will not be written to the alert log for
the next minute. Please look at trace files to see all
the ORA-20 errors.

According  to oracle docs :

Error:  ORA 20  
Text:   maximum number of processes <num> exceeded
-------------------------------------------------------------------------------

Cause :  An operation requested a resource that was unavailable. The maximum number of processes is specified by the initialization parameter PROCESSES. When this maximum is reached, no more requests are processed.

Action : Try the operation again in a few minutes. If this message occurs often, shut down Oracle, increase the PROCESSES parameter in the initialization parameter file, and restart Oracle.

Finally , i have decided to increase the no. of processes but didn't find any exact formula or any optimal value  to set this parameter . So i have set it to 200 for now . Another issue here with us to connect with oracle, since we getting error while connecting with oracle . Here is one trick to create a session  by using  "Prelim" option . Interesting things about this option is that we can only use the "shut abort" command nothing else (AFAIK).  Here are the steps to set the processes value : 

[oracle@server1 ~]$  sqlplus -prelim  "sys/xxxx as sysdba"
SQL*Plus: Release 11.2.0.1.0 Production on Fri May 24 13:38:55 2013
Copyright (c) 1982, 2009, Oracle.  All rights reserved.

SQL> shut immediate
ORA-01012: not logged on

SQL>  shut abort
ORACLE instance shut down.

SQL> exit 

Once the instance is down we can easily increase the process value at mount stage  .

[oracle@server1 ~]$ sqlplus "sys/sys as sysdba"
SQL*Plus: Release 11.2.0.1.0 Production on Fri May 24 13:51:40 2013
Copyright (c) 1982, 2009, Oracle.  All rights reserved.
Connected to an idle instance.

SQL> startup mount
ORACLE instance started.

Total System Global Area  418484224 bytes
Fixed Size                  1336932 bytes
Variable Size             310380956 bytes
Database Buffers          100663296 bytes
Redo Buffers                6103040 bytes
Database mounted.

SQL> alter system set processes=200 scope=spfile;
System altered.

SQL> shut immediate
ORA-01109: database not open

Database dismounted.
ORACLE instance shut down.

SQL> startup
ORACLE instance started.

Total System Global Area  418484224 bytes
Fixed Size                  1336932 bytes
Variable Size             310380956 bytes
Database Buffers          100663296 bytes
Redo Buffers                6103040 bytes
Database mounted.
Database opened.

SQL> select name,open_mode from v$database;
NAME      OPEN_MODE
--------- --------------------
ORCL      READ WRITE


Impact on db while increasing the processes  :: 

While googling , i found a very useful comment  by "Jonathan Lewis" .According to him , Increasing processes from say 1000 to 5000 increases the amount of shared memory that needs to be reserved  at the O/S level and disrupt the memory in the SGA. The OS must be configured to support the larger amount of shared memory.

The impact at the O/S is that every process that starts up will want to build a memory map for the SGA - depending on the way we have configured memory pages and the way that strategy our O/S adopts to build maps it could demand a huge amount of O/S memory in a short time. The technology we need to avoid this issue comes in two different flavours: large memory pages, and shared memory maps.

The impact on the SGA is two-fold - each process and session has to create an entry in v$process and v$session, and allocate various memory structures in the SGA: acquiring the rows in v$session and v$process are serial actions, and the memory allocation in the SGA can cause massive flushing of the library cache . 

So , it is advisable to increase the number of processes while keeping it's impact in mind .


Enjoy    :-) 

Largest Databases of the World

Greetings Everyone :  I am  back after a  long break . I  was  busy  in some other  aspects of my life and now i have decided to keep updating this blog to share my knowledge and experience with you all . It's always give me a great feeling when i share some this with you all and learn alot from you guys through your mails , comments and chat.

One  day , i  was thinking  about  some scenario's  about  a  large database  then  one  thing  click  in my mind i.e, "What  is the size of  the largest database in  this world" and  what  database are  they using ? I guess, it  may be  google  and  then  search on net  and  find  some  interesting  facts  which  i will like to share you all . Let’s get started and just keep in mind that size alone does not determine how big a database is, it’s the information it contains in the form of fields and records  and eventually it all depends on the technology being employed for storage and management. 

No 1. The World Data Centre for Climate (WDCC) : 

WDCC is  Operated  by  the Max Planck Institute for Meteorology and German Climate Computing Centre, The  World  Data Centre  for Climate  is  the largest database in the world with 220 terabytes of data that is readily available on the internet. Add to that 110 terabytes of climate simulation data and 6 petabytes of data stored on magnetic tapes.

The  WDCC  is  included  in  the CERA  database system. Access  to  the  CERA  database  is possible from  the Internet  by  use  of  a Java- based  browser. The  CERA ( Climate  and  Environmental Retrieving and Archiving) - data archive is realised on an ORACLE database connected to a STK Silo system. Thus  large data  sets  may  be stored under control of this System while the metadata associated with CERA permit an easy way to relocate data, which have to be retrieved.

No 2. National Energy Research Scientific Computing Center  (NERSCC) :

Based  in Oakland, California, National  Energy Research  Scientific Computing Center or NERSC is owned and operated by the Lawrence and  the  U.S.  Department of  Energy.  Included in its  database of 2.8 petabytes  is  information on  atomic energy  research, high energy physics experiments and simulations of the early universe.

The High Performance Storage System (HPSS) is a modern, flexible, performance-oriented mass storage system.  It has been used at NERSC for archival storage since 1998.

No 3.  AT&T :

Bigger than sprint, AT&T boasts 1.9 trillion calling records which contribute to 323 terabytes worth of information. One  factor behind  the  massiveness  of  its database  is the fact that AT&T has been maintaining databases from the time when the technology to store terabytes wasn’t even available.

The  Daytona®  data management  system  is  used  by AT&T to solve a wide spectrum of data management problems. For example, Daytona  is  managing  over 312 terabytes of data in a 7x24 production  data warehouse  whose largest  table  contains over 743 billion records as of Sept 2005. Indeed, for  this  database, Daytona  is managing over 1.924  trillion records; it  could easily manage more but  we  ran  out of  data. Update: as of June 2007, Daytona is managing over 2.8 trillion records in  this same data warehouse, with over 938 billion records in the largest table.

AT&T  is  the  sole source for the Daytona product, service and support and is the only company authorized to use the Daytona trademark for a database product.

No 4. Google  :

The   list  wouldn't  be  complete  without  Google. Subjected  to  around  100  million  searches per day, Google  is one  of  the  largest databases  in  the  world  that  has over 33  trillion  database entries. Although  the  exact size of Google’s database  is unknown, it’s  said  that Google  accounts every  single search  that  makes  each day into  its  database which  is  around 91 million  searches per day. Google  stores  every  search and  makes patterns  from  previous  searches so  that  the user can be  easily directed. Google also  collects  information  of their users and stores them as entries in their database which is said to expand over 33 trillion entries. On top of that Google has simply expanded their database with Gmail and Google ads and with their acquisitions like YouTube. 

Bigtable  is  a  distributed  storage  system (built by Google)  for  managing  structured data  that  is designed to scale to a very large size: petabytes of data across thousands of commodity servers.Many projects  at Google  store data in Bigtable, including web indexing, Google Earth, and Google Finance. These applications place very different demands on Bigtable, both in terms of data size (from URLs to web pages to satellite imagery) and latency requirements (from backend bulk processing to real-time data serving).

No 5. Sprint  :

The third largest wireless telecommunications network in the US has a database of over 55 million users. Sprint processes over 365 million call detail records per day. Making up its huge database are 2.85 trillion rows of information.

No 6. LexisNexis  :

LexisNexis  is  a  company providing  computer-assisted  legal  research  services  which  bought Choicepoint  in 2008 , and   Choicepoint  was  in  the  business of  acquiring  inform ation  about  the American  population  including  everything  from  phone numbers to criminal histories. It had  over 250 terabytes of data on  the  American population  until it was bought by LexisNexis .

No 7. YouTube  :

With over  60 hours  of video  uploaded  per  minute, yes,  per minute, YouTube  has a  video  database of  around  45 terabytes. It  has  over 100 million  videos  being  watched every  day  Reports say that about a 100 million  videos are  watched in  YouTube which is about 60% of the  overall number of videos watched online.

No 8. Amazon  :

Containing  records of more than 60 million  active users, Amazon also has more than 250,000 full text books available online and allows users to comment and interact on  virtually every page of the website. Overall, the Amazon database is over 42 terabytes in size.

Amazon SimpleDB is a highly available and flexible non-relational data store that offloads the work of database administration. Developers simply store and query data items via web services requests and Amazon SimpleDB does the rest.

No 9. Central Intelligence Agency  :

With  exact  size  understandably  not  made  public, the  CIA  has  comprehensive  statistics on  more than 250  countries  of  the world  and  also collects  and distributes  information  on  people, places and things. Although,  the database  is  not  open to public, portions  of  it  are  made available. Freedom of Information Act (FOIA)  Electronic  Reading  Room  is  one  such  example  where  100s  of items are  added  from  the  database  monthly.

The  ARC  maintains  an  automated  system  containing  information  concerning  each  individual accession ("job"). The A RC database  includes  detailed  information  at  the  file  folder level for each accession retired  after  1978,  including  the  job  number, box  and  file number,  file  title, level  of security classification, inclusive dates, and  disposition  instructions, including  date  when  disposition action  will  be taken. Less detailed information is maintained for accessions retired before 1978.

No 10.  Library of Congress  :

With  over  130  million  items  including  29  million  books,  photographs  and  maps, 10,000  new items added  each  day and nearly  530 miles  of  shelves, the Library  of  Congress  is a wonder to behold in itself. Only  the  text  portion of  the  library would  take up  20  terabytes  of  space.  If internet  isn’t helping  you  ou t in  your  research, head  to  the oldest  federal cultural  institution  in  the United States in DC.

The  Library of  Congress  offers a  wide variety  of  online databases  and  Internet  resources  to  the public via  the Web, including  its  own  online  catalog.  In  addition, LC provides  an easy-to-use gateway  for  searching  other  institutions' online  catalogs  and  extensive  links  to  resources  on  the Internet.

Souce ::  http://globtech24x7.com/10-largest-databases-of-the-world/


Enjoy   :-)