Introduction to the Multitenant Architecture
Multitenant Architecture:
Multitenant Architecture was first introduced in version 12c and is getting better with each version of Oracle.
Before 12c, each Oracle database was just a single bank, with its SGA, PGA and so on. This architecture is known as non-CDB. This architecture was deprecated from 12c. In other words, Oracle has already warned that in the future it would no longer be supported and that everyone should move to the CDB architecture and use all its benefits.
Currently, Oracle has already warned that as of version 20c, the non-CDB architecture is no longer supported! That is, if you still don't use Multitenant, you should start immediately!
A CDB bank has zero or more Pluggable Database (PDBs). A PDB is nothing more than a collection of schemas, schema objects, nonschema objects and so on. So, each PDB is like a non-CDB bank, and this is transparent to anyone who connects to the PDB!
Multitenant is an option! That is, we can create only one PDB per CDB without buying this option. But, what is the advantage then? Well, there are some things that are much easier in a CDB architecture, such as patches, upgrades, etc. And the good news is that starting with version 19c, we can have 3 PDBS per CDB without needing the Multitenant option!
To begin studies on this new architecture, we will install Oracle 19c on Oracle Linux 7.7. We already have here on the blog how to install Linux. Now let's see how to install Oracle 19c, using the .zip package. The installation has changed slightly since version 18c. In this example we will use the option to install in silient mode. That is, without using the graphical interface, GUI, which should be the standard of any DBA. We will use a response file.
Download it from the Oracle website, update your Linux and install the oracle-database-preinstall-19c package.
As root user do the following:
# mkdir -p /u01/app/oracle # mkdir -p /u01/app/oraInventory # chown -R oracle:oinstall /u01/app/oracle # chown -R oracle:oinstall /u01/app/oraInventory # chmod -R 775 /u01/app
Now, as an oracle user:
$ mkdir -p /u01/app/oracle/product/19.0.0/dbhome_1 $ cd /u01/app/oracle/product/19.0.0/dbhome_1 $ unzip -q /home/oracle/LINUX.X64_193000_db_home.zip
Well, the Oracle binaries are already OK. Now we are going to install Oracle using a response file.
There is a model file at $ ORACLE_HOME / install / response / db_install.rsp. Open this file and edit as desired, being able to copy to another location. See how mine was just to install the software, without creating a bank, we will do it separately later.
####################################################################
## Copyright(c) Oracle Corporation 1998,2019. All rights reserved.##
## ##
## Specify values for the variables listed below to customize ##
## your installation. ##
## ##
## Each variable is associated with a comment. The comment ##
## can help to populate the variables with the appropriate ##
## values. ##
## ##
## IMPORTANT NOTE: This file contains plain text passwords and ##
## should be secured to have read permission only by oracle user ##
## or db administrator who owns this installation. ##
## ##
####################################################################
#------------------------------------------------------------------------------
# Do not change the following system generated value.
#------------------------------------------------------------------------------
oracle.install.responseFileVersion=/oracle/install/rspfmt_dbinstall_response_schema_v19.0.0
#-------------------------------------------------------------------------------
# Specify the installation option.
# It can be one of the following:
# - INSTALL_DB_SWONLY
# - INSTALL_DB_AND_CONFIG
#-------------------------------------------------------------------------------
oracle.install.option=INSTALL_DB_SWONLY
#-------------------------------------------------------------------------------
# Specify the Unix group to be set for the inventory directory.
#-------------------------------------------------------------------------------
UNIX_GROUP_NAME=oinstall
#-------------------------------------------------------------------------------
# Specify the location which holds the inventory files.
# This is an optional parameter if installing on
# Windows based Operating System.
#-------------------------------------------------------------------------------
INVENTORY_LOCATION=/u01/app/oraInventory
#-------------------------------------------------------------------------------
# Specify the complete path of the Oracle Base.
#-------------------------------------------------------------------------------
ORACLE_BASE=/u01/app/oracle
#-------------------------------------------------------------------------------
# Specify the installation edition of the component.
#
# The value should contain only one of these choices.
# - EE : Enterprise Edition
# - SE2 : Standard Edition 2
#-------------------------------------------------------------------------------
oracle.install.db.InstallEdition=EE
###############################################################################
# #
# PRIVILEGED OPERATING SYSTEM GROUPS #
# ------------------------------------------ #
# Provide values for the OS groups to which SYSDBA and SYSOPER privileges #
# needs to be granted. If the install is being performed as a member of the #
# group "dba", then that will be used unless specified otherwise below. #
# #
# The value to be specified for OSDBA and OSOPER group is only for UNIX based #
# Operating System. #
# #
###############################################################################
#------------------------------------------------------------------------------
# The OSDBA_GROUP is the OS group which is to be granted SYSDBA privileges.
#-------------------------------------------------------------------------------
oracle.install.db.OSDBA_GROUP=dba
#------------------------------------------------------------------------------
# The OSOPER_GROUP is the OS group which is to be granted SYSOPER privileges.
# The value to be specified for OSOPER group is optional.
#------------------------------------------------------------------------------
oracle.install.db.OSOPER_GROUP=oper
#------------------------------------------------------------------------------
# The OSBACKUPDBA_GROUP is the OS group which is to be granted SYSBACKUP privileges.
#------------------------------------------------------------------------------
oracle.install.db.OSBACKUPDBA_GROUP=backupdba
#------------------------------------------------------------------------------
# The OSDGDBA_GROUP is the OS group which is to be granted SYSDG privileges.
#------------------------------------------------------------------------------
oracle.install.db.OSDGDBA_GROUP=dgdba
#------------------------------------------------------------------------------
# The OSKMDBA_GROUP is the OS group which is to be granted SYSKM privileges.
#------------------------------------------------------------------------------
oracle.install.db.OSKMDBA_GROUP=kmdba
#------------------------------------------------------------------------------
# The OSRACDBA_GROUP is the OS group which is to be granted SYSRAC privileges.
#------------------------------------------------------------------------------
oracle.install.db.OSRACDBA_GROUP=racdba
################################################################################
# #
# Root script execution configuration #
# #
################################################################################
#-------------------------------------------------------------------------------------------------------
# Specify the root script execution mode.
#
# - true : To execute the root script automatically by using the appropriate configuration methods.
# - false : To execute the root script manually.
#
# If this option is selected, password should be specified on the console.
#-------------------------------------------------------------------------------------------------------
oracle.install.db.rootconfig.executeRootScript=true
#--------------------------------------------------------------------------------------
# Specify the configuration method to be used for automatic root script execution.
#
# Following are the possible choices:
# - ROOT
# - SUDO
#--------------------------------------------------------------------------------------
oracle.install.db.rootconfig.configMethod=ROOT
#--------------------------------------------------------------------------------------
# Specify the absolute path of the sudo program.
#
# Applicable only when SUDO configuration method was chosen.
#--------------------------------------------------------------------------------------
oracle.install.db.rootconfig.sudoPath=
#--------------------------------------------------------------------------------------
# Specify the name of the user who is in the sudoers list.
# Applicable only when SUDO configuration method was chosen.
# Note:For Single Instance database installations,the sudo user name must be the username of the user installing the database.
#--------------------------------------------------------------------------------------
oracle.install.db.rootconfig.sudoUserName=
###############################################################################
# #
# Grid Options #
# #
###############################################################################
#------------------------------------------------------------------------------
# Value is required only if the specified install option is INSTALL_DB_SWONLY
#
# Specify the cluster node names selected during the installation.
#
# Example : oracle.install.db.CLUSTER_NODES=node1,node2
#------------------------------------------------------------------------------
oracle.install.db.CLUSTER_NODES=
###############################################################################
# #
# Database Configuration Options #
# #
###############################################################################
#-------------------------------------------------------------------------------
# Specify the type of database to create.
# It can be one of the following:
# - GENERAL_PURPOSE
# - DATA_WAREHOUSE
# GENERAL_PURPOSE: A starter database designed for general purpose use or transaction-heavy applications.
# DATA_WAREHOUSE : A starter database optimized for data warehousing applications.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.type=GENERAL_PURPOSE
#-------------------------------------------------------------------------------
# Specify the Starter Database Global Database Name.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.globalDBName=
#-------------------------------------------------------------------------------
# Specify the Starter Database SID.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.SID=
#-------------------------------------------------------------------------------
# Specify whether the database should be configured as a Container database.
# The value can be either "true" or "false". If left blank it will be assumed
# to be "false".
#-------------------------------------------------------------------------------
oracle.install.db.ConfigureAsContainerDB=false
#-------------------------------------------------------------------------------
# Specify the Pluggable Database name for the pluggable database in Container Database.
#-------------------------------------------------------------------------------
oracle.install.db.config.PDBName=
#-------------------------------------------------------------------------------
# Specify the Starter Database character set.
#
# One of the following
# AL32UTF8, WE8ISO8859P15, WE8MSWIN1252, EE8ISO8859P2,
# EE8MSWIN1250, NE8ISO8859P10, NEE8ISO8859P4, BLT8MSWIN1257,
# BLT8ISO8859P13, CL8ISO8859P5, CL8MSWIN1251, AR8ISO8859P6,
# AR8MSWIN1256, EL8ISO8859P7, EL8MSWIN1253, IW8ISO8859P8,
# IW8MSWIN1255, JA16EUC, JA16EUCTILDE, JA16SJIS, JA16SJISTILDE,
# KO16MSWIN949, ZHS16GBK, TH8TISASCII, ZHT32EUC, ZHT16MSWIN950,
# ZHT16HKSCS, WE8ISO8859P9, TR8MSWIN1254, VN8MSWIN1258
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.characterSet=
#------------------------------------------------------------------------------
# This variable should be set to true if Automatic Memory Management
# in Database is desired.
# If Automatic Memory Management is not desired, and memory allocation
# is to be done manually, then set it to false.
#------------------------------------------------------------------------------
oracle.install.db.config.starterdb.memoryOption=false
#-------------------------------------------------------------------------------
# Specify the total memory allocation for the database. Value(in MB) should be
# at least 256 MB, and should not exceed the total physical memory available
# on the system.
# Example: oracle.install.db.config.starterdb.memoryLimit=512
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.memoryLimit=
#-------------------------------------------------------------------------------
# This variable controls whether to load Example Schemas onto
# the starter database or not.
# The value can be either "true" or "false". If left blank it will be assumed
# to be "false".
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.installExampleSchemas=false
###############################################################################
# #
# Passwords can be supplied for the following four schemas in the #
# starter database: #
# SYS #
# SYSTEM #
# DBSNMP (used by Enterprise Manager) #
# #
# Same password can be used for all accounts (not recommended) #
# or different passwords for each account can be provided (recommended) #
# #
###############################################################################
#------------------------------------------------------------------------------
# This variable holds the password that is to be used for all schemas in the
# starter database.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.password.ALL=
#-------------------------------------------------------------------------------
# Specify the SYS password for the starter database.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.password.SYS=
#-------------------------------------------------------------------------------
# Specify the SYSTEM password for the starter database.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.password.SYSTEM=
#-------------------------------------------------------------------------------
# Specify the DBSNMP password for the starter database.
# Applicable only when oracle.install.db.config.starterdb.managementOption=CLOUD_CONTROL
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.password.DBSNMP=
#-------------------------------------------------------------------------------
# Specify the PDBADMIN password required for creation of Pluggable Database in the Container Database.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.password.PDBADMIN=
#-------------------------------------------------------------------------------
# Specify the management option to use for managing the database.
# Options are:
# 1. CLOUD_CONTROL - If you want to manage your database with Enterprise Manager Cloud Control along with Database Express.
# 2. DEFAULT -If you want to manage your database using the default Database Express option.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.managementOption=DEFAULT
#-------------------------------------------------------------------------------
# Specify the OMS host to connect to Cloud Control.
# Applicable only when oracle.install.db.config.starterdb.managementOption=CLOUD_CONTROL
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.omsHost=
#-------------------------------------------------------------------------------
# Specify the OMS port to connect to Cloud Control.
# Applicable only when oracle.install.db.config.starterdb.managementOption=CLOUD_CONTROL
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.omsPort=0
#-------------------------------------------------------------------------------
# Specify the EM Admin user name to use to connect to Cloud Control.
# Applicable only when oracle.install.db.config.starterdb.managementOption=CLOUD_CONTROL
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.emAdminUser=
#-------------------------------------------------------------------------------
# Specify the EM Admin password to use to connect to Cloud Control.
# Applicable only when oracle.install.db.config.starterdb.managementOption=CLOUD_CONTROL
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.emAdminPassword=
###############################################################################
# #
# SPECIFY RECOVERY OPTIONS #
# ------------------------------------ #
# Recovery options for the database can be mentioned using the entries below #
# #
###############################################################################
#------------------------------------------------------------------------------
# This variable is to be set to false if database recovery is not required. Else
# this can be set to true.
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.enableRecovery=false
#-------------------------------------------------------------------------------
# Specify the type of storage to use for the database.
# It can be one of the following:
# - FILE_SYSTEM_STORAGE
# - ASM_STORAGE
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.storageType=
#-------------------------------------------------------------------------------
# Specify the database file location which is a directory for datafiles, control
# files, redo logs.
#
# Applicable only when oracle.install.db.config.starterdb.storage=FILE_SYSTEM_STORAGE
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.fileSystemStorage.dataLocation=
#-------------------------------------------------------------------------------
# Specify the recovery location.
#
# Applicable only when oracle.install.db.config.starterdb.storage=FILE_SYSTEM_STORAGE
#-------------------------------------------------------------------------------
oracle.install.db.config.starterdb.fileSystemStorage.recoveryLocation=
#-------------------------------------------------------------------------------
# Specify the existing ASM disk groups to be used for storage.
#
# Applicable only when oracle.install.db.config.starterdb.storageType=ASM_STORAGE
#-------------------------------------------------------------------------------
oracle.install.db.config.asm.diskGroup=
#-------------------------------------------------------------------------------
# Specify the password for ASMSNMP user of the ASM instance.
#
# Applicable only when oracle.install.db.config.starterdb.storage=ASM_STORAGE
#-------------------------------------------------------------------------------
oracle.install.db.config.asm.ASMSNMPPassword=
Now, let's install Oracle Software.
$ ./runInstaller -silent -responseFile /home/oracle/db19c.rsp Launching Oracle Database Setup Wizard... Enter password for 'root' user: The response file for this session can be found at: /u01/app/oracle/product/19.0.0/dbhome_1/install/response/db_2020-02-10_06-22-44PM.rsp You can find the log of this install session at: /tmp/InstallActions2020-02-10_06-22-44PM/installActions2020-02-10_06-22-44PM.log Successfully Setup Software. Moved the install session logs to: /u01/app/oraInventory/logs/InstallActions2020-02-10_06-22-44PM $
Simple isn't it? Is fast! Now that the software is already installed, let's create a CDB bank without any PDB, that is, empty. For that, we will use another response file as well. The model for this file can be found in $ ORACLE_HOME / assistants / dbca / dbca.rsp. Edit as desired, which is the same thing you would do via the screen. Now, let's run createDatabase silent with the response file.
$ dbca -silent -createDatabase -responseFile /home/oracle/dbca.rsp Enter SYS user password: Enter SYSTEM user password: Prepare for db operation 4% complete Creating and starting Oracle instance 5% complete 6% complete 8% complete Creating database files 9% complete 13% complete Creating data dictionary views 14% complete 16% complete 19% complete 20% complete 21% complete 23% complete 25% complete Oracle JVM 31% complete 38% complete 44% complete 46% complete Oracle Text 48% complete 50% complete Oracle Multimedia 63% complete Oracle OLAP 67% complete Oracle Spatial 68% complete 75% complete Creating cluster database views 76% complete 83% complete Completing Database Creation 86% complete 88% complete Executing Post Configuration Actions 100% complete Database creation complete. For details check the logfiles at: /u01/app/oracle/cfgtoollogs/dbca/cdb1. Database Information: Global Database Name:cdb1 System Identifier(SID):cdb1 Look at the log file "/u01/app/oracle/cfgtoollogs/dbca/cdb1/cdb1.log" for further details.
Now our CDB bank is created, still without any PDB, empty. It looks like the image below:
See that we have our CDB bank, but we also have the PDB $ SEED. It is a template that comes with the CDB Database and serves to create new PDBs. You cannot create or modify objects within SEED.
We are going to create a PDB now, using PDB $ SEED, in the simplest possible way, specifying only the name of the PDB together with its user who manages the PDB.
$ export ORACLE_SID=cdb1 [oracle@terciocosta1 ~]$ sqlplus / as sysdba SQL*Plus: Release 19.0.0.0.0 - Production on Fri Feb 14 15:33:39 2020 Version 19.3.0.0.0 Copyright (c) 1982, 2019, Oracle. All rights reserved. Connected to: Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production Version 19.3.0.0.0 SQL> CREATE PLUGGABLE DATABASE pdb1 ADMIN USER pdb1adm IDENTIFIED BY oracle; Pluggable database created. SQL> column name format a10 SQL> column open_mode format a10 SQL> column pdb_name format a10 SQL> column status format a10 SQL> SELECT name, open_mode FROM v$pdbs; NAME OPEN_MODE ---------- ---------- PDB$SEED READ ONLY PDB1 MOUNTED SQL> SELECT pdb_name, status FROM DBA_PDBS; PDB_NAME STATUS ---------- ---------- PDB$SEED NORMAL PDB1 NEW SQL> ALTER PLUGGABLE DATABASE pdb1 OPEN; Pluggable database altered. SQL> SELECT pdb_name, status FROM DBA_PDBS; PDB_NAME STATUS ---------- ---------- PDB$SEED NORMAL PDB1 NORMAL SQL> SELECT name, open_mode FROM v$pdbs; NAME OPEN_MODE ---------- ---------- PDB$SEED READ ONLY PDB1 READ WRITE
We just created our first PDB and we can see some features. First it is mounted, we need to open the bank. His status is new, but after the bank opens it changes. When creating a new PDB, a new service_name with the same name as the PDB is automatically created, but it will be necessary to manually create an entry in tnsnames.ora. After creating some PDBS, our CDB looks like the image below.
Now that we have created a CDB bank with some PDBs, let's look at some features and advantages of the multitenant architecture.
One of the main advantages of this architecture is to consolidate many databases, minimizing the effort, people and hardware needed to maintain these banks. Instead of having 100 separate banks on several servers each with its own SGA, PGA, data files, users, backups, etc., we can consolidate all of this with a single CDB bank with a single SGA, PGA and so on. As a result, the number of DBAs needed to maintain this also decreases.
Before consolidating the foundations
This consolidation is easy to implement, as each PDB behaves as if it were a non-CDB bank. Using the multitenant architecture, it also has advantages to perform tasks directly at the CDB, such as backup and Data Guard, where it applies to all PDBs existing at the CDB.
After consolidation
When carrying out such a consolidation, we have reduced costs because we use the resources of a single server more efficiently. We can quickly monitor and manage a single CDB server and bank instead of multiple non-CDB banks spread across multiple servers. There are other advantages that I will talk about in the following posts, but in short the best advantages would be when applying patches and performing upgrades that is much easier and faster.
For each PDB to have its own data dictionary, we have some facilities, as each PDB is like a separate unit. An advantage of this is that we can unplug a CDB PDB and plug that PDB into a CDB with a larger version, thus performing an upgrade. This also makes it easy to migrate between servers, we can flash back to just one PDB and so on. Even cloning a base in this architecture just got a lot easier! This helps a lot when creating test and development environments. We have the option to also create a snapshot of a PDB that is a point-in-time copy, the snapshots can also be configured with a fixed interval of time or a snapshot that is updated from time to time with source PDB!
Source: Oracle Internals & word press
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