oracle database 11g database architecture and asm

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Oracle Database 11g Architecture

Learning objective

After completing this topic, you should be able to identify the characteristics of elements

of the Oracle Database 11g architecture.

1. The Oracle database

Disclaimer

Although certain aspects of the Oracle 11g Database are case and spacing insensitive, a

common coding convention has been used throughout all aspects of this course.

This convention uses lowercase characters for schema, role, user, and constraint names,

and for permissions, synonyms, and table names (with the eception of the D!A" table#.

"owercase characters are also used for column names and user$defined procedure,

function, and variable names shown in code.

!ppercase characters are used for Oracle %eywords and functions, for view, table,

schema, and column names shown in tet, for column aliases that are not shown in

&uotes, for pac%ages, and for data dictionary views.

The spacing convention re&uires one space after a comma and one space before and

after operators that are not Oracle$specific, such as ', $, , and ). There should be nospace between an Oracle$specific %eyword or operator and an opening brac%et, between

a closing brac%et and a comma, between the last part of a statement and the closing

semicolon, or before a statement.

*tring literals in single &uotes are an eception to all of the convention rules provided

here. +lease use this convention for all interactive parts of this course.

End of Disclaimer

The Oracle elational Database -anagement *ystem (D-*# is a database

management system that provides an open, comprehensive, integrated approach toinformation management. A database is a collection of data treated as a unit. The

purpose of a database is to store and retrieve related information.

An Oracle Database reliably manages a large amount of data in a multi$user environment

so that many users can concurrently access the same data. This is accomplished while

delivering high performance. At the same time, the database prevents unauthori/ed

access and provides efficient solutions for failure recovery.
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An Oracle Database consists of an instance and its associated databases. The instance

consists of memory structures and bac%ground processes. 0very time an instance is

started, a shared memory area called the *ystem lobal Area (*A# is allocated and the

bac%ground processes are started.

The database consists of both physical structures and logical structures. ecause the

physical and logical structures are separate, the physical storage of data can be

managed without affecting access to logical storage structures.

2onnection and session are closely related to user process but are very different in

meaning.

A connection is a communication pathway between a user process and an Oracle

Database instance. A communication pathway is established using either of the following

two mechanisms3

available inter$process communication mechanisms 4 on a computer that runs both the userprocess and Oracle Database

networ% software 4 when different computers run the database application and Oracle Database,

and communicate through a networ%

A session represents the state of a current user login to the database instance. 5or

eample, when a user starts *6"7+lus, the user must provide a valid username and

password, and then a session is established for that user.

A session lasts from the time the user connects until the time the user disconnects or

eits the database application.

8n the case of a dedicated connection, the session is serviced by a permanent dedicated

process. The session is serviced by an available server process selected from a pool,

either by the middle tier or by the Oracle shared server architecture.

-ultiple sessions can be created and eist concurrently for a single Oracle Database user

using the same username. 5or eample, a user with the usernamepassword of HRHR

can connect to the same Oracle Database instance several times.

After starting an instance, the Oracle software associates the instance with a specific

database. This is called mounting the database. The database is then ready to be

opened, which ma%es it accessible to authori/ed users.

-ultiple instances can eecute concurrently on the same computer, each accessing its

own physical database.

9ou can loo% at the Oracle Database architecture as various interrelated structural

components.


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An Oracle instance uses memory structures and processes to manage and access the

database. All memory structures eist in the main memory of the computers that

constitute the database server.

+rocesses are :obs that wor% in the memory of these computers. A process is defined as

a ;thread of control; or a mechanism in an operating system that can run a series of

steps.

2. tructures and architecture

Oracle Database creates and uses memory structures for various purposes. 5or eample,

memory stores program code being run, data shared among users, and private data

areas for each connected user.

Two basic memory structures are associated with an instance3

*ystem lobal Area (*A#

+rogram lobal Areas (+As#

!stem "lobal Area #"A$

The *ystem lobal Area (*A# is a group of shared memory structures, %nown as *A

components, that contain data and control information for one Oracle Database instance.

The *A is shared by all server and bac%ground processes. 0amples of data stored in

the *A include cached data bloc%s and shared *6" areas.

Program "lobal Areas #P"As$

The +rogram lobal Areas (+As# are memory regions that contain data and control

information for a server or bac%ground process. A +A is non$shared memory created by

Oracle Database when a server or bac%ground process is started. Access to the +A is

eclusive to the server process. 0ach server process and bac%ground process has its own

+A.

The *A is the memory area that contains data and control information for the instance.

The *A includes the following data structures3

database buffer cache

redo log buffer

shared pool

large pool


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redo log buffer

The redo log buffer caches redo information 4 used for instance recovery 4 until it can be

written to the physical redo log files stored on the dis%.

shared %ool

The shared pool caches various constructs that can be shared among users.

large %ool

The large pool is an optional area that provides large memory allocations for certain large

processes, such as Oracle bac%up and recovery operations, and 8O server processes.

&ava %ool

The


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8n addition, the Oracle server has a set of bac%ground processes for an instance that

interact with each other and with the operating system to manage the memory structures

and asynchronously perform 8O to write data to dis%, and perform other re&uired tas%s.

The process structure varies for different Oracle Database configurations, depending on

the operating system and the choice of Oracle Database options. The code for connected

users can be configured as a dedicated server or a shared server.

>ith a dedicated server, for each user, the database application is run by a user process

that is served by a dedicated server process that eecutes Oracle database server code.

A shared server eliminates the need for a dedicated server process for each connection.

A dispatcher directs multiple incoming networ% session re&uests to a pool of shared

server processes. A shared server process serves any client re&uest.

Oracle Database creates server processes to handle the re&uests of user processes

connected to the instance.

8n some situations when the application and Oracle Database operate on the same

computer, it is possible to combine the user process and corresponding server process

into a single process to reduce system overhead.

owever, when the application and Oracle Database operate on different computers, a

user process always communicates with Oracle Database through a separate server

process.

*erver processes created on behalf of each user?s application can perform one or more

of these tas%s3

parsing and running *6" statements issued through the application

reading necessary data bloc%s from data files on dis% into the shared database buffers of the

*A, if the bloc%s are not already present in the *A

returning results in such a way that the application can process the information

To maimi/e performance and accommodate many users, a multi$process Oracle

Database system uses some additional Oracle Database processes called bac%ground

processes. An Oracle Database instance can have many bac%ground processes.

The bac%ground processes commonly seen in non$A2 non$A*- environments can

include these3

Database >riter process (D>n#

"og >riter process (">#

2hec%point process (2B+T#


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*ystem -onitor process (*-OC#

+rocess -onitor process (+-OC#

ecoverer process (02O#

ithout them, you cannot open data

files to access the data within the database.

data files

Data files contain the user or application data of the database, as well as metadata and the

data dictionary.online redo log files

Online redo log files allow for instance recovery of the database. 8f the database server

crashes and does not lose any data f iles, then the instance can recover the database with

the information in these files.

5urther Oracle Database files are depicted.

parameter file

password file

bac%up files

archived redo log files

trace files

alert log file

%arameter file

The parameter file is used to define how the instance is configured when it starts up.


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%ass'ord file

The password file allows sysdbasysopersysasm to connect remotely to the database and

perform administrative tas%s.

bac(u% files

ac%up files are used for database recovery. 9ou typically restore a bac%up file when amedia failure or user error has damaged or deleted the original file.

archived redo log files

Archived redo log files contain an ongoing history of the data changes 4 redo 4 that are

generated by the instance. !sing these files and a bac%up of the database, you can

recover a lost data file. That is, archive logs enable the recovery of restored data files.

trace files

0ach server and bac%ground process can write to an associated trace file. >hen an

internal error is detected by a process, the process dumps information about the error to its

trace file. *ome of the information written to a trace file is intended for the databaseadministrator, whereas other information is for Oracle *upport *ervices.

alert log file

Alert log files are special trace entries. The alert log of a database is a chronological log of

messages and errors. 0ach instance has one alert log f ile. Oracle recommends that you

review this periodically.

)uestion

>hich files constitute an Oracle database

Options3

1. Archive redo log files

E. 2ontrol f iles

F. Data files

G. Online redo log files

H. +arameter f iles

Ans'er

2ontrol files, data files, and online redo log files are the three files that constitutean Oracle Database 11g database.

Option 1 is incorrect. Archive redo logs contain a history of data changes

generated by the instance. They can be used to recover a lost data file. However,

archive redo logs are not essential in the everyday use of the database.


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Option 2 is correct. Control files are small binary files which are necessary to start

and use the database. f control files are missing or corrupt, then you cannot open

the data files to access the data.

Option ! is correct. A tablespace is made up of at least one data file. A data file

can be assigned to only one tablespace and only a single database. The data file

contains essential information such as user and application data.

Option " is correct. Online redo logs are essential for instance recovery for the

database. The redo logs are used to recover modified data which was not written

to the data files prior to a failure.

Option # is incorrect. $arameter files are important to successfully run an Oracle

database. However, they do not ma%e up the actual database. $arameter files are

used to define how the instance is configured when it starts up.

*. Logical and %h!sical database structures

The database has logical structures and physical structures.

A database is divided into logical storage units called tablespaces, which group related

logical structures together. 5or eample, tablespaces commonly group all of an

application?s ob:ects to simplify some administrative operations.

9ou may have a tablespace for application data and an additional one for application

indees.

0ach database is logically divided into one or more tablespaces. One or more data files

are eplicitly created for each tablespace to physically store the data of all logical

structures in a tablespace. 8f it is a TEMPORARYtablespace, then instead of a data file, the

tablespace has a temporary file.

A schema is a collection of database ob:ects that are owned by a database user. *chema

ob:ects are the logical structures that directly refer to the database?s data.

*chema ob:ects include such structures as tables, views, se&uences, stored procedures,

synonyms, indees, clusters, and database lin%s. 8n general, schema ob:ects include

everything that your application creates in the database.

At the finest level of granularity, an Oracle database?s data is stored in data bloc%s. One

data bloc% corresponds to a specific number of bytes of physical database space on the

dis%. A database uses and allocates free database space in Oracle data bloc%s.

The net level of logical database space is called an etent. An etent is a specific

number of contiguous data bloc%s (obtained in a single allocation# that are used to store a

specific type of information.


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are eplicitly created for each tablespace to physically store the data of all logical

structures in a tablespace. Data files belong to only one tablespace.

9ou can also create bigfile tablespaces. These tablespaces can have only a single file,

which is often very large.

,ote

The file may be any si&e up to ma'imum that the row ( architecture will permit.

The ma'imum si&e is the bloc% si&e for the tablespace times 2 to the !)th power,

or 12* T+ for a !2 + bloc% si&e. The traditional smallfile tablespaces -which are

the default usually contain multiple data files, but the files cannot be as large.

0ach Oracle database must contain a SYSTEMtablespace and a SYSAUXtablespace.

They are automatically created when the database is created.

The system default is to create a smallfile tablespace. 9ou can also create bigfile

tablespaces, which enable the Oracle database to manage ultralarge files 4 up to I

eabytes in si/e.

A tablespace can be online (accessible# or offline (not accessible#. The SYSTEM

tablespace is always online when the database is open. 8t stores tables that support the

core functionality of the database, such as the data dictionary tables.

The SYSAUXtablespace is an auiliary tablespace to the SYSTEMtablespace. The

SYSAUXtablespace stores many database components, and it must be online for the

correct functioning of all database components.

,ote

The SYSAUXtablespace may be ta%en offline to do tablespace recovery, whereas

this is not possible for the SYSTEMtablespace. /either of them may be made

read0only.

Database ob:ects, such as tables and indees, are stored as segments in tablespaces.

0ach segment contains one or more etents. An etent consists of contiguous data

bloc%s, which means that each etent can eist only in one data file. Data bloc%s are the

smallest unit of 8O in the database.

>hen the database re&uests a set of data bloc%s from the operating system (O*#, the O*

maps this to an actual file system or dis% bloc% on the storage device. ecause of this,

you need not %now the physical address of any of the data in your database. This also

means that a data file can be striped or mirrored on several dis%s.


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The si/e of the data bloc% is defined by the DB_BLOCK_SIZEparameter. The default si/e

of I B is ade&uate for most databases. 8f your database supports a data warehouse

application that has large tables and indees, then a larger bloc% si/e may be beneficial.

8f your database supports a transactional application where reads and writes are random,

then specifying a smaller bloc% si/e may be beneficial. The maimum bloc% si/e dependson your O*. 9ou can have tablespaces with a non$standard bloc% si/e.

The structural components of Oracle Database are

memory structures

process structures

storage structures

memor! structures

-emory structures are

*ystem lobal Area (*A# 4 database buffer cache, redo buffer, and various pools

+rogram lobal Area (+A#

%rocess structures

+rocess structures are

user process and server process

bac%ground processes 4 *-OC, +-OC, D>n, 2B+T,">, A2n, and so on

storage structures

*torage structures are

logical 4 database, schema, tablespace, segment, etent, and Oracle bloc%

physical 4 data files, control files, and redo log files

)uestion

>hich are logical structures in Oracle Database 11g

Options3

1. A data file

E. An operating system bloc%

F. A schema

G. A tablespace

Ans'er

*chemas and tablespaces are logical storage structures in Oracle Database 11g.


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Option 1 is incorrect. (ata files are physical structures that store the data of all the

logical structures in a tablespace.

Option 2 is incorrect. An operating system bloc% is a physical structure. t is the

smallest storage unit used to store the actual data for a database and its si&e is

dependent upon the operating system itself.

Option ! is correct. A schema is a collection of database obects that are owned

by a database user. chema obects are logical structures that refer to a

database3s data.

Option " is correct. An Oracle (atabase 11g database is divided into logical

storage units called tablespaces. A tablespace groups related logical structures

together.

)uestion

>hat statements are true regarding the SYSTEMtablespace in Oracle Database

11g

Options3

1. The SYSTEMtablespace can be ta%en offline

E. The SYSTEMtablespace is automatically created when the database is created

F. The SYSTEMtablespace is optional

G. The SYSTEMtablespace stores tables that support the core functionality of the

database

Ans'er

The SYSTEMtablespace is automatically created when the database is created. 8t

stores tables that support the core functionality of the database.

Option 1 is incorrect. Although the SYSAUXtablespace can be ta%en offline for

tablespace recovery, the SYSTEMtablespace cannot. The SYSTEMtablespace

must be online for the database to function.

Option 2 is correct. 4hen an Oracle (atabase 11g database is created, both the

SYSTEMand SYSAUXtablespaces are created automatically for you. These

tablespaces store information needed for the correct functioning of the database.

Option ! is incorrect. 5ach Oracle (atabase 11g database must contain a SYSTEM

and SYSAUXtablespace. The SYSTEMtablespace is a mandatory tablespace

re6uired for the core functionality of the database.


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Option " is correct. The SYSTEMtablespace contains the information needed by

the Oracle (atabase 11g database to function properly. This information is stored

in tables such as the data dictionary tables.

ummar!

A database is a collection of data treated as a unit. 8t consists of both physical structures

and logical structures.

Oracle Database creates and uses memory structures for various purposes. *ystem

lobal Area (*A# and +rogram lobal Areas (+As# are basic memory structures

associated with an instance.

A database is divided into logical storage units called tablespaces. 0ach Oracle database

must contain a SYSTEMtablespace and a SYSAUXtablespace. The SYSAUXtablespace is

an auiliary tablespace to the SYSTEMtablespace.

Table of Contents

| To% of %age|

| Learning objective|

| 1. The Oracle database|

| 2. tructures and architecture|

| *. Logical and %h!sical database structures|

| ummar!|

2opyright J E@@K *%ill*oft. All rights reserved.

*%ill*oft and the *%ill*oft logo are trademar%s or registered trademar%s

of *%ill*oft in the !nited *tates and certain other countries.

All other logos or trademar%s are the property of their respective owners.


A- and Dis( "rou%s Overvie'

Learning objective

After completing this topic, you should be able to recognize the steps for managing

database files using Automatic Storage Management (ASM) and dis groups.
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1. Automatic torage -anagement #A-$

Automatic *torage -anagement (A*-# provides a vertical integration of the file system

and the volume manager that is specifically built for the Oracle database files.

A*- can provide management for single symmetric multiprocessor (*-+# machines, or

across multiple nodes of a cluster for Oracle eal Application 2lusters (A2# support.

A single A*- instance can provide support for many Oracle databases simultaneously.

A*- distributes 8O load across all available resources to optimi/e performance while

removing the need for manual 8O tuning.

A*- helps DAs to manage a dynamic database environment by allowing them to

increase the database si/e without having to shut down the database to ad:ust the

storage allocation.

A*- can maintain redundant copies of data to provide fault tolerance, or it can be built on

top of vendor$supplied reliable storage mechanisms.

A*- may use virtual raw volumes provided in a storage area networ% (*AC# environment

or /ero$padded files on a networ% attached storage (CA*# filer in addition to using local

raw devices.

Data management is done by selecting the desired reliability and performance

characteristics for classes of data rather than with human interaction on a per file basis.

A*- capabilities save DAs? time by automating manual storage and thereby increasing

their ability to manage larger databases and more of them with increased efficiency.

A*- divides files into allocation units (A!s# and spreads the A!s for each file evenly

across all the dis%s.

A*- uses an inde techni&ue to trac% the placement of each A!. >hen your storage

capacity changes, A*- does not restripe all of the data, but moves an amount of data

proportional to the amount of storage added or removed to evenly redistribute the files

and maintain a balanced load across the dis%s. This is done while the database is up.

9ou can increase the speed of a rebalance operation, or lower it to reduce the impact onthe 8O subsystem.

A*- provides mirroring protection without the need to purchase a third$party "ogical

=olume -anager. One uni&ue advantage of A*- is that the mirroring is applied on a file

basis, rather than on a volume basis. Therefore, the same dis% group can contain a

combination of files protected by mirroring, along with those that are not protected at all.


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A*- supports data files, log files, control files, archive logs, temp files, archive log files,

*+58"0s, -AC bac%up sets, and other Oracle database file types.

A*- supports eal Application 2lusters and eliminates the need for a 2luster "ogical

=olume -anager or a 2luster 5ile *ystem.

)uestion

ow does Automatic *torage -anagement (A*-# benefit database administrators

(DAs#

Options3

1. 8t enables them to manage larger and more databases with increased efficiency

E. 8t forces databases to be shut down before ad:usting storage allocation

F. 8t provides more human interaction on a per file basis

G. 8t provides support for only a single Oracle database

Ans'er

A*- enables DAs to manage larger and more databases with increased

efficiency.

Option 1 is correct. +y automating manual storage, A7 capabilities save (+As

time. This increases their ability to manage larger and more databases with

increased efficiency.

Option 2 is incorrect. A7 allows (+As to manage dynamic databases, includingadusting the storage allocation without shutting down the databases first.

Option ! is incorrect. A73s data management is done by selecting the desired

reliability and performance characteristics for classes of data. This prevents the

(+A from wor%ing with data on a per file basis.

Option " is incorrect. A single A7 instance can provide simultaneous support for

many Oracle (atabase 11g databases.

2. Creating an A- instance

To use A*-, you must start a special instance, called an A*- instance, before you start

your database instance.

A*- instances do not mount databases 4 instead they manage the metadata needed to

ma%e A*- files available to ordinary database instances.


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oth A*- instances and database instances have access to some common set of dis%s

called dis% groups. Database instances access the contents of A*- files directly,

communicating with an A*- instance only to get information about the layout of these

files.

An A*- instance starts several bac%ground processes specific to A*-. One process

coordinates rebalance activity for dis% groups. 8t is called RBAL.

The second one performs the actual rebalance A! movements. There can be many of

these at a time, and they are called ARB0, ARB1, and so forth.

The GMONprocess, or roup -onitor, is used for partner and status table, and node

membership. An A*- instance also has some of the same bac%ground processes as a

database instance, including SMON, PMON, LGWR, DBWR, and CKPT.

0ach database instance using A*- has two etra bac%ground processes called ASMB

and RBAL.

RBALperforms global opens of the dis%s in the dis% groups. At database instance startup,

ASMBconnects as a foreground process to the A*- instance. 2ommunication between

the database and the A*- instance is performed via this bridge. This includes physical

file changes such as data file creation and deletion.

Over this connection, periodic messages are echanged to update statistics and to verify

that both instances are healthy.

9ou create an A*- instance by running the Database 2onfiguration Assistant (D2A#.

On the first page, you select the 2onfigure Automatic *torage -anagement option, and

then follow the steps.

The A*- instance is created and started for you. Then you are guided through the

process of defining dis% groups for the instance.

As part of the A*- instance creation process, the D2A automatically creates an entry

into the oratafile. This entry is used for discovery purposes.

On the >indows platform where a services mechanism is used, the D2A automatically

creates an Oracle *ervice and the appropriate registry entry to facilitate the discovery ofA*- instances.

8n addition, you are prompted to run the !o"a!"o#%&script that configures 2luster

*ynchroni/ation *ervices to manage the A*- instance. >hen an A*- instance is

configured, the D2A creates an A*- instance parameter file and an A*- instance

password file.


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8f you were to create an A*-$enabled database, the D2A determines whether an A*-

instance already eists on your host. 8f A*- instance discovery returns an empty list, the

D2A creates a new A*- instance.

)uestion

>hat is the purpose of the ASMBbac%ground process that is created for each

database instance using Automatic *torage -anagement (A*-#

Options3

1. 8t coordinates rebalance activity for dis% groups

E. 8t mounts the database that will use A*-

F. 8t performs the actual rebalance movements of the allocation units

G. 8t provides communication between the database and the A*- instance

Ans'er

The purpose of the ASMBbac%ground process is to provide communication

between the database and the A*- instance.

Option 1 is incorrect. The bac%ground process RBALcoordinates rebalance

activity for dis% groups. This process is started when the A7 instance is started.

Option 2 is incorrect. The ASMBprocess does not mount the database. t provides

communication between the A7 instance and the database instance.

Option ! is incorrect. The actual rebalance movements are performed by anumber of processes, including ARB0, ARB1, and others.

Option " is correct. The ASMBprocess connects to the A7 instance when the

database instance starts. Communication between the database and the A7

instance is performed by this process, including physical file changes, such as

creation and deletion.

)uestion

>hich is a correct statement about an A*- instance

Options3

1. After the A*- instance is started, the database will be mounted

E. Once the A*- instance has been created, you must define your dis% groups

manually

F. The A*- instance can share the same dis% group as your database

G. The A*- instance must be started manually after it has been created by the D2A


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re&uire low latency, A*- provides fine$grained (1EI B# striping. 8inestriping stripes

each A!.

A*- uses coarse$ or fine$grain striping on the basis of file type.

5ine striping brea%s up medium$si/ed 8O operations into multiple smaller 8O operations

that eecute in parallel. >hile the number of files and dis%s increase, you have to

manage only a constant number of dis% groups.

5rom a database perspective, dis% groups can be specified as the default location for files

created in the database.

,ote

5ach dis% group is self0describing, containing its own file directory and dis%

directory.

*uppose you want to upgrade the database storage from file system files to A*-. To do

this, you use D2A to create an A*- instance called (ASMand configure two dis%

groups, DATAand )RA.

The DATAdis% group uses four F raw slices employing normal redundancy. The )RA

dis% group uses four L slices employing eternal redundancy.

There are 1F steps you must perform to upgrade the database storage to A*-. The first

two steps are3

te% 13 9ou invo%e the Database 2onfiguration Assistant (D2A# and you clic% ,e+tonthe >elcome screen to get started.

te% 23 On the net page, you select Configure Automatic torage -anagementfrom

the list of possible operations, and then clic% ,e+t to continue.

The net three steps to upgrade the database storage to A*- are3

te% *3 9ou are as%ed to run the !o"a!"o#%&script to set up local 2luster

*ynchroni/ation *ervice (2**# for high availability purposes.

te% 3 9ou open a terminal window and run the !o"a!"o#%& a++script as root.

>hen the script has completed, you clic% O/to dismiss the localconfig dialog bo.

te% 03 After returning to the Operations page, you clic% ,e+tto continue.

The net three steps are3


20/44


21/44

0ternal redundancy does not provide mirroring. 9ou use an eternal$redundancy dis%

group if you use hardware mirroring or if you can tolerate data loss as the result of a dis%

failure. 5ailure groups are not used with this type of dis% group.

normal7redundanc!

Cormal redundancy supports two$way mirroring.high7redundanc!

igh redundancy provides triple mirroring.

A*- does not mirror dis%s 4 rather, it mirrors A!s. As a result, you need only spare

capacity in your dis% group.

>hen a dis% fails, A*- automatically reconstructs the contents of the failed dis% on the

surviving dis%s in the dis% group by reading the mirrored contents from the surviving

dis%s. This spreads the 8O hit from a dis% failure across several dis%s.

>hen A*- allocates a primary A! of a file to one dis% in a dis% group, it allocates a mirror

copy of that A! to another dis% in the dis% group.

+rimary A!s on a given dis% can have their mirror copies on one of several partner dis%s

in the dis% group. A*- ensures that a primary A! and its mirror copy never reside in the

same failure group.

8f you define failure groups for your dis% group, A*- can tolerate the simultaneous failure

of multiple dis%s in a single failure group.

>ith A*-, the rebalance process is very easy and happens without any intervention from

the DA or system administrator. A*- automatically rebalances a dis% group whenever

dis%s are added or dropped. owever, rebalancing will be delayed when dis% groups are

dropped because of errors.

y using inde techni&ues to spread A!s on the available dis%s, A*- does not need to

restripe all of the data, but instead needs to only move an amount of data proportional to

the amount of storage added or removed to evenly re$distribute the files and maintain a

balanced 8O load across the dis%s in a dis% group.

>ith the 8O balanced whenever files are allocated and whenever the storage

configuration changes, the DA never needs to search for hot spots in a dis% group and

manually move data to restore a balanced 8O load. owever, because the databaseneeds to resync cached A*- metadata, rebalances will have less impact if done in &uiet

periods.

8t is more efficient to add or drop multiple dis%s at the same time so that they are

rebalanced as a single operation. This avoids unnecessary movement of data. >ith this

techni&ue, it is easy to achieve online migration of your data. All you need to do is add the

new dis%s in one operation and drop the old ones in one operation.


22/44

9ou can control how much of a load the rebalance operation has on the system by setting

the ASM_POWER_LIMITparameter. 8ts range of values is 1 through 11. The lower the

number, the lighter the load 4 a higher setting has more of a load and finishes sooner.

ummar!

Automatic *torage -anagement (A*-# provides a vertical integration of the file system

and the volume manager that is specifically built for the Oracle database files.

To use A*-, you must start a special instance, called an A*- instance, before you start

your database instance. A*- instances manage the metadata needed to ma%e A*- files

available to ordinary database instances.

A dis% group is a collection of dis%s managed as a logical unit. *torage is added and

removed from dis% groups in units of A*- dis%s. A*- has three dis% group types that

support different types of mirroring 4 eternal$redundancy, normal$redundancy, and high$

redundancy.

Table of Contents

| To% of %age|


| 1. Automatic torage -anagement #A-$|

| 2. Creating an A- instance|

| *. A- dis( grou%s|

| ummar!|

2opyright J E@@L *%ill*oft. All rights reserved.





-anaging Dis( "rou%s

Learning objective

After completing this topic, you should be able to identify !ays to manage dis groups

and their attributes and also configure and manage ASM instances.
http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#pagetophttp://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#pagetophttp://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#objectivehttp://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#section_1http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#section_2http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#section_3http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#section_3http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#summaryhttp://%20window.print%28%29/http://%20window.print%28%29/http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#contentshttp://%20parent.window.close%28%29/http://%20parent.window.close%28%29/http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#pagetophttp://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#objectivehttp://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#section_1http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#section_2http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#section_3http://library.skillport.com/courseware/cbtlib/256882/256885/eng/thin/transcript.html#summaryhttp://%20window.print%28%29/http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#contentshttp://%20parent.window.close%28%29/


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1. -anaging dis( grou%s

The main goal of an A*- instance is to manage dis% groups and protect their data. A*-

instances also communicate file layout to database instances. 8n this way, database

instances can directly access files stored in dis% groups.

There are several dis% group administrative commands. They all re&uire the SYSASMor

SYSDBAprivilege and must be issued from an A*- instance. 9ou can add new dis%

groups. 9ou can also modify eisting dis% groups to add new dis%s, remove eisting ones,

and perform many other operations. 9ou can remove eisting dis% groups.

9ou can use the *6"7+lus to manage dis% groups. Assume that A*- dis% discovery

identified the following dis%s in the -+,.%",/directory3 A1, A, A, B1, B, and B. Also,

assume that dis%s A1, A, and Aare on a separate *2*8 controller from dis%s B1, B,

and B. The first eample illustrates how to configure a dis% group called DGROUPAwith

two failure groups 4CONTROLLER1

andCONTROLLER

.

The eample also uses the default redundancy characteristic, NORMAL REDUNDANCY, for

the dis% group.

CREATE DISKGROUP +&ro23A NORMAL REDUNDANCY

)AILGROUP "o#tro!!,r1 DISK

4-+,.%",/-A14 NAME +%/5A1 SIZE 10G )ORCE6

4-+,.%",/-A46

4-+,.%",/-A4

)AILGROUP "o#tro!!,r DISK

4-+,.%",/-B146

4-+,.%",/-B46

4-+,.%",/-B47

9ou can optionally provide a dis% name and si/e for the dis%. 8f you do not supply this

information, A*- creates a default name and attempts to determine the si/e of the dis%. 8f

the si/e cannot be determined, an error is returned. )ORCEindicates that a specified dis%

should be added to the specified dis% group even though the dis% is already formatted as

a member of an A*- dis% group. !sing the )ORCEoption for a dis% that is not formatted

as a member of an A*- dis% group returns an error.

9ou can delete a dis% group along with all its files. To avoid accidental deletions, theINCLUDING CONTENTSoption must be specified if the dis% group still contains any files

besides internal A*- metadata. The dis% group must be mounted in order for it to be

dropped.

After ensuring that none of the dis% group files are open, the group and all its drives are

removed from the dis% group. Then the header of each dis% is overwritten to eliminate the

A*- formatting information.


24/44


25/44

D-* compatibility refers to the minimum compatible version of the D-* instance

that would allow the instance to mount the dis% group. This compatibility dictates the

format of messages that are echanged between the A*- and database (D-*#

instances. An A*- instance has the capability to support different D-* clients running

at different compatibility settings. The database compatible version setting of each

instance must be greater than or e&ual to the D-* compatibility of all dis% groups

used by that database.

Database instances are typically run from a different Oracle home than the A*- instance.

This implies that the database instance may be running a different software version than

the A*- instance. >hen a database instance first connects to an A*- instance, it

negotiates the highest version that they both can support. The compatibility parameter

setting of the database, software version of the database, and the D-* compatibility

setting of a dis% group determine whether a database instance can mount a given dis%

group.

A*- compatibility refers to the persistent compatibility setting controlling the format of

data structures for A*- metadata on dis%. The A*- compatibility level of a dis% group

must always be greater than or e&ual to the D-* compatibility level of the same dis%

group. A*- compatibility is concerned only with the format of the A*- metadata.

The format of the file contents is up to the database instance. 5or eample, the A*-

compatibility of a dis% group can be set to 11.@ while its D-* compatibility could be

[email protected]. This implies that the dis% group can be managed only by A*- software whose

software version is 11.@ or higher, whereas any database client whose software version is

higher than or e&ual to [email protected] can use that dis% group.

The compatibility of a dis% group needs to be advanced only when there is a change to

either persistent dis% structures or protocol messaging. owever, advancing dis% group

compatibility is an irreversible operation. 9ou can set the dis% group compatibility by using

either the CREATE DISKGROUPor ALTER DISKGROUPcommands.

,ote

n addition to the dis% group compatibilities, the compatible parameter ; database

compatible version ; determines the features that are enabled. t applies to the

database or A7 instance depending on the instancehenever you create or alter an A*- dis% group, you have the ability to change its

attributes using the new ATTRIBUTEclause of the CREATE DISKGROUPand ALTER

DISKGROUPcommands.


26/44

CREATE DISKGROUP DATA NORMAL REDUNDANCY

DISK 4-+,.-ra>-ra>1464-+,.-ra>-ra>4

ATTRIBUTE 4"o?3at%!,'a/?4@411'147

A*- enables the use of different allocation unit (A!# si/es that you can specify when you

create a dis% group. The A! can be 1, E, G, I, 1L, FE, or LG - in si/e.

9ou can specify the DISK_REPAIR_TIMEin units of minute (-#, hour (#, or day (D#. 8f

you omit the unit, then the default is . 8f you omit this attribute, then the default is F.L.

9ou can override this attribute with an ALTER DISKGROUP ''' DISK O))LINE

statement.

9ou can also specify the redundancy attribute of the specified template, the striping

attribute of the specified template, D-* compatibility, and A*- compatibility.

,ote

8or each defined dis% group, you can loo% at all defined attributes through the

V$ASM_ATTRIBUTEfi'ed view.

0nterprise -anager provides a simple way to store and retrieve environment settings

related to dis% groups.

On the Dis% roups tabbed page of the Automatic *torage -anagement page, you clic%

the dis% name 4DATA.

9ou then clic% the Editbutton.

9ou can set the compatible attributes from both the create dis% group page and the 0dit

Advanced Attributes for Dis% roup3 Data page. The +%/5_r,3a%r_t%?,attribute is

added to the 0dit Advanced Attributes for Dis% roup3 Data page only.

,ote

8or pre011g A7 instances, the default A7 compatibility and client compatibility

is 1=.1. 8or 11g A7 instances, the default A7 compatibility is 1=.1 and

database compatibility is 1=.1.

2. A- instances

The SYSASMrole is specifically intended for performing A*- administration tas%s. !sing

the SYSASMrole instead of the SYSDBArole improves security by separating A*-

administration from database administration.

8n Oracle Database 11g elease 1, the O* group for SYSASMand SYSDBAis the same,


27/44

and the default installation group for SYSASMis +a. 8n a future release, separate groups

will have to be created, and SYSDBAusers will be restricted in A*- instances. 2urrently,

as a member of the +agroup you can connect to an A*- instance using the first

statement.

SL CONNECT - AS SYSASMSL CREATE USER o///a/?2/,r#a?, IDENTI)IED 3a//>+7

SL GRANT SYSASM TO o///a/?2/,r#a?,7

SL CONNECT o///a/?2/,r#a?, - 3a//>+ AS SYSASM7

SL DROP USER o///a/?2/,r#a?,7

,ote

n Oracle (atabase 11g 9elease 1, if you log in to an A7 instance as SYSDBA,

warnings are written in the corresponding a!,rt'!o&file.

9ou can also use the combination of CREATE USERand GRANT SYSASM *6"statements from an A*- instance to create a new SYSASMuser. This is possible as long

as the name of the user is an eisting O* username. These commands update the

password file of each A*- instance, and do not need the instance to be up and running.

*imilarly, you can revo%e the SYSASMrole from a user using the REVOKEcommand, and

you can drop a user from the password file using the DROP USERcommand. The

V$PW)ILE_USERSview includes a new column called SYSASMthat indicates whether the

user can connect with SYSASMprivileges 4 TRUE4 or not 4 )ALSE.

A*- instances are started similarly to database instances ecept that the initiali/ation

parameter file contains the entry INSTANCE_TYPE@ASM. >hen this parameter is set to

the value A*-, it informs the Oracle eecutable that an A*- instance is starting, not a

database instance. Also, the ORACLE_SIDvariable must be set to the A*- instance

name. >hen the A*- instance starts up, the mount stage attempts to mount the dis%

groups specified by the ASM_DISKGROUPSinitiali/ation parameter rather than mounting a

database, as is done with non$A*- instances.

Other STARTUPclauses have comparable interpretation for A*- instances as they do for

database instances. OPENis invalid for an A*- instance. NOMOUNTstarts up the A*-

instance without mounting the database.

$ ,3ort ORACLE_SID@4(ASM4

$ /!3!2/ -#o!o&

SL CONNECT - AS //a/?

Co##,"t,+ to a# %+!, %#/ta#",'

SL STARTUP7

Tota! S/t,? G!oa! Ar,a


28/44

Var%a!, S%F, 9


29/44

This is the only parameter that you need to set for complete A7 memory

management. Oracle Corporation strongly recommends that you use automatic

memory management for A7.

A*- instances do not have a data dictionary, so the only way to connect to one is by

using O* authentication, that is,SYSASM

,SYSDBA

, orSYSOPER

. To connect remotely, a

password file must be used. !sers who connect to the A*- instance with the SYSASMor

SYSDBAprivileges have administrative access to all dis% groups in the system. The

SYSOPERprivilege is supported in A*- instances and limits the set of allowable *6"

commands to the minimum re&uired for basic operation of an already configured system.

These commands are available to SYSOPERusers3

STARTUP-SHUTDOWN

ALTER DISKGROUP MOUNT-DISMOUNT

ALTER DISKGROUP ONLINE-O))LINE DISK

ALTER DISKGROUP REBALANCE

ALTER DISKGROUP CHECK

SELECT a!! V$ASM_= .%,>/

All other commands, such as CREATE DISKGROUP, ADD-DROP-RESIZE DISKre&uire

the SYSASMor SYSDBAprivilege and are not allowed with the SYSOPERprivilege.

>hen you attempt to shut down an A*- instance in the NORMAL, IMMEDIATE, or

TRANSACTIONALmodes, it succeeds only if there are no database instances connected

to the A*- instance. 8f there is at least one connected instance, you receive an error.

ORA190;J "a##ot SHUTDOWN ASM %#/ta#", >%t "o##,"t,+ RDBMS

%#/ta#",

8f you perform a SHUTDOWN ABORTon the A*- instance, it shuts down, and it will re&uire

recovery at the time of the net startup. Any connected database instances will also

eventually shut down, reporting an error.

ORA190:8J "o??2#%"at%o# a%!2r, >%t ASM %#/ta#",

8n a single$A*- instance configuration, if the A*- instance fails while dis% groups areopen for update, then after the A*- instance reinitiali/es, it reads the dis% group?s log

and recovers all transient changes. >ith multiple A*- instances sharing dis% groups, if

one A*- instance fails, another A*- instance automatically recovers transient A*-

metadata changes caused by the failed instance.

The failure of a database instance does not affect A*- instances. The A*- instance

should be started automatically whenever the host is rebooted. The A*- instance is


30/44

epected to use the automatic startup mechanism supported by the underlying operating

system. 5ile system failure usually crashes a node.

0nterprise -anager allows you to manage the users who access the A*- instance

through remote connection, using password file authentication. These users are reserved

eclusively for the A*- instance.

9ou have this functionality only when you are connected as the SYSASMuser. 8t is hidden

if you connect as SYSDBAor SYSOPERusers.

9ou clic% the Createbutton.

The 2reate !ser page is displayed.

,ote

Oracle (atabase 11g adds the SYSASMrole to the A7 instance login page.

9ou can edit an eisting user by selecting the electchec%bo, then clic%ing theEdit

button.

The 0dit !ser page is displayed.

On the !sers page, you clic% the Deletebutton to delete the created users.

)uestion

>hich parameter must be defined in an A*- parameter file

Options3

1. ASM_DISKSTRING

E. ASM_POWER_LIMIT

F. DB_UNIUE_NAME

G. INSTANCE_TYPE

Ans'er

The only parameter that must be defined in an A*- parameter file is

INSTANCE_TYPE.

Option 1 is incorrect. The ASM_DISKSTRINGparameter is optional and is an

operating system0dependent value used by A7 to limit the set of dis%s

considered for discovery.


31/44

Option 2 is incorrect. ASM_POWER_LIMITis an optional parameter that controls

the speed for a rebalance operation and can have values from 1 through 11. f

omitted, the default value is 1.

Option ! is incorrect. DB_UNIUE_NAMEis an optional parameter that specifies

the service provider name for which this A7 instance manages dis% groups.

Option " is correct. 8or A7 instances, the INSTANCE_TYPEparameter should

be set to A7. This is the only parameter that must be defined.

)uestion

>hat is the purpose of the ASM_DISKGROUPSparameter in an A*- parameter

file

Options3

1. 8nforming the Oracle eecutable that an A*- instance is starting

E. Opening the A*- instance

F. *pecifying the dis% group to attempt to mount at startup

G. *pecifying the set of dis%s considered for discovery

Ans'er

The purpose of the ASM_DISKGROUPSparameter in an A*- parameter file is to

specify the dis% group to attempt to mount at startup.

Option 1 is incorrect. The parameter file entry INSTANCE_TYPE @ ASMinforms

the Oracle e'ecutable that an A7 instance is starting, not the ASM_DISKGROUPS

parameter.

Option 2 is incorrect. An A7 instance is started not opened. >nli%e other

STARTUPclauses that have comparable interpretations for A7 instances as they

do for database instances, the OPENclause is invalid for an A7 instance.

Option ! is correct. 4hen an A7 instance starts up, the mount stage attempts to

mount the dis% groups specified by the ASM_DISKGROUPSinitiali&ation parameter.

Option " is incorrect. The initiali&ation parameter ASM_DISKSTRINGis used by

A7 to limit the set of dis%s considered for discovery, not the ASM_DISKGROUPS

parameter.

)uestion


32/44

Different users have different levels of administrative access when connected to

an A*- instance.

>hich user has limited administrative access when connected to an A*-

instance

Options3

1. SYSASM

E. SYSDBA

F. SYSOPER

Ans'er

A SYSOPERuser has the minimum re&uired administrative access when connected

to an A*- instance.

Option 1 is incorrect. >sers who have the SYSASMprivileges have administrative

access to all dis% groups in the system. And they can perform all operations

necessary for maintaining the A7 instance.

Option 2 is incorrect. The SYSDBAprivilege provides full administrative access to

all the dis% groups for the A7 instance. >sers with this privilege can perform all

necessary operations on the A7 instance.

Option ! is correct. The SYSOPERprivilege limits the set of allowable ?@

commands to the minimum re6uired for the basic operation of an already

configured system.

ummar!

To manage dis% groups, there are several dis% group administrative commands available

which re&uire the SYSASMor SYSDBAprivilege. There are two compatibility settings that

are attributes of each A*- dis% group 4 D-* compatibility, and A*- compatibility.

>henever you create or alter an A*- dis% group, you have the ability to change its

attributes.

The SYSASMrole is specifically intended for performing A*- administration tas%s. AnA*- instance is controlled by a parameter file in the same way as a regular database

instance. The failure of a database instance does not affect A*- instances. The A*-

instance should be started automatically whenever the host is rebooted.

Table of Contents


33/44

| To% of %age|


| 1. -anaging dis( grou%s|

| 2. A- instances|

| ummar!|

2opyright J E@@L *%ill*oft. All rights reserved.





A- torage

Learning objective

After completing this topic, you should be able to recognize the steps for managing ASM

storage, scalability, and performance using the A"#$% command and also the ASM&MD

utility.

1. A- storage conce%ts

A*- does not eliminate any eisting database functionality. 0isting databases are able

to operate as they always have. Cew files may be created as A*- files, whereas eisting

ones are administered in the old way or can be migrated to A*-.

There are new concepts introduced by A*- in Oracle Database 1@g to describe file

storage. These concepts do not replace any eisting concepts such as segments and

tablespaces. >ith A*-, database files can now be stored as A*- files. At the top of the

new hierarchy are A*- dis% groups.

Any single A*- file is contained in only one dis% group. owever, a dis% group may

contain files belonging to several databases, and a single database may use storage

from multiple dis% groups.

One dis% group is made up of A*- dis%s, and each A*- dis% belongs to only one dis%

group. Also, A*- files are always spread across all the A*- dis%s in the dis% group. A*-

dis%s are partitioned in allocation units (A!s# of one megabyte each. An A! is the

smallest contiguous dis% space that A*- allocates. A*- does not allow physical bloc%s

to be split across A!s.
http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#pagetophttp://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#pagetophttp://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#objectivehttp://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#section_1http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#section_2http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#summaryhttp://%20window.print%28%29/http://%20window.print%28%29/http://library.skillport.com/courseware/cbtlib/256882/256953/eng/thin/transcript.html#contentshttp://%20parent.window.close%28%29/http://%20parent.window.close%28%29/http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#pagetophttp://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#objectivehttp://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#section_1http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#section_2http://library.skillport.com/courseware/cbtlib/256882/256950/eng/thin/transcript.html#summaryhttp://%20window.print%28%29/http://library.skillport.com/courseware/cbtlib/256882/256953/eng/thin/transcript.html#contentshttp://%20parent.window.close%28%29/


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9ou have already used D2A to create an A*- instance called 'A*- and configure two

dis%groups, DATA and 5A. 9ou now need to migrate your database storage to use A*-.

9ou connect to 0nterprise -anager using the !" https3your


35/44

9ou wait a few moments and log bac% in to 0nterprise -anager. 9ou clic% the A-lin%

on the database home page.

On the 'A*- home page, the DATAdis%group is associated with the or"!instance

storage.

After the database has been migrated to A*-, you can remove all the files that were

stored in the traditional file system.

2. ALTE8 commands

This statement shows how to remove one of the dis%s from the DGROUPAdis% group.

ALTER DISKGROUP +&ro23A DROP DISK A97

ALTER DISKGROUP +&ro23A

DROP DISK A:

ADD )AILGROUP r,+

DISK 4-+,.-r+/5-"0t


36/44

This statement rebalances the DGROUPBdis% group, if necessary.

This command is generally not necessary because it is automatically done as dis%s are

added, dropped, or resi/ed. owever, it is useful if you want to use the POWERclause to

override the default speed defined by the initiali/ation parameter ASM_POWER_LIMIT.

9ou can change the power level of an ongoing rebalance operation by reentering the

command with a new level. A power level of /ero causes rebalancing to halt until the

command is either implicitly or eplicitly reinvo%ed.

ALTER DISKGROUP +&ro23B REBALANCE POWER 97

This statement dismounts DGROUPA.

The MOUNTand DISMOUNToptions allow you to ma%e one or more dis% groups available

or unavailable to the database instances. The ability to manually unmount and mount is

useful in a clustered A*- environment supporting a single instance, when that instance isfailed over to a different node.

ALTER DISKGROUP +&ro23A DISMOUNT7

)uestion

9ou want to drop dis% Cfrom the dis% group named DGROUPB.

>hich *6" statement would you use

Options3

1. ALTER DISKGROUP +&ro23 DROP C7

E. ALTER DISKGROUP +&ro23 DROP DISK C7

F. ALTER DISKGROUP DROP DISK C7

G. ALTER GROUP +&ro23 DROP DISK C7

Ans'er

To drop a dis% from a dis% group, you use this command3

ALTER DISKGROUP +&ro23 DROP DISK C7

Option 1 is incorrect. ou must include the DROP DISKcommand to drop a dis%

from a dis% group.


37/44

Option 2 is correct. To drop a dis%, you use ALTER DISKGROUPand include the

dis% group3s name, followed by the DROP DISKcommand and the name of the

dis% you wish to drop.

Option ! is incorrect. To drop a dis%, the ?@ statement must include the name of

the dis% group to which the dis% belongs.

Option " is incorrect. ou use ALTER DISKGROUPto drop a dis%, not ALTER

GROUP.

)uestion

9ou want to ma%e dis% group DGROUPBunavailable to the database instances.

>hich *6" statement would you use

Options3

1. ALTER DISK +&ro23 DISMOUNT7

E. ALTER DISKGROUP +&ro23 DISMOUNT7

F. ALTER DISKGROUP DISMOUNT7

G. ALTER GROUP +&ro23 DISMOUNT7

Ans'er

To ma%e a dis% group unavailable to the database instances, you use the

DISMOUNToption of the ALTER DISKGROUPcommand.

Option 1 is incorrect. The correct command to ma%e a dis% group unavailable is

ALTER DISKGROUP, not ALTER DISK.

Option 2 is correct. The DISMOUNToption of the ALTER DISKGROUPcommand

ma%es the specified dis% group unavailable to the database instances. This is

useful in a clustered A7 environment supporting a single instance, when that

instance is failed over to a different node.

Option ! is incorrect. 4hen using the ALTER DISKGROUPcommand to dismount

a dis% group, you must specify the name of the dis% group.

Option " is incorrect. The correct command to ma%e a dis% group unavailable is

ALTER DISKGROUP, not ALTER GROUP.

*. A-C-D utilit!


38/44

A*-2-D is a command line utility that you can use to view and manipulate files and

directories within A*- dis% groups. A*-2-D can list the contents of dis% groups,

perform searches, create and remove directories and aliases, display space utili/ation,

and more. A*-2-D wor%s with A*- files, directories, and aliases.

0very file created in A*- gets a system$generated file name, otherwise %nown as a fully

&ualified file name. This is the same as a complete path name in a local file system. As in

other file systems, an A*- directory is a container for files, and an A*- directory can be

part of a tree structure of other directories. The fully &ualified file name represents a

hierarchy of directories in which the plus sign ('# represent the root directory.

SL CREATE TABLESPACE t/a/? DATA)ILE 4(DGROUP14 SIZE 100M7

Ta!,/3a", "r,at,+'

SL CREATE TABLESPACE ra33/ DATA)ILE 4(DGROUP14 SIZE 10M7

Ta!,/3a", "r,at,+'

$ ,3ort ORACLE_SID@(ASM

$ a/?"?+

ASMCMD !/ ! DGROUP1-ORCL-DATA)ILE

T3, R,+2#+ Str%3,+ T%?, S/ Na?,

DATA)ILE MIRROR COARSE OCT 09 1J00J00 Y HRAPPS'9;'9;0:11

DATA)ILE MIRROR COARSE OCT 09 1J00J00 Y TBSASM'9:'9;01;

ASMCMD

9ou can create your own directories as subdirectories of the system$generated directories

using the A*-2-D ?5+%rcommand.

ASMCMD ?5+%r (+&ro231-/a?3!,-?+%r

A*-2-D can perform A*- metadata bac%up and restore functionality. This provides the

ability to re$create a pre$eisting A*- dis% group with the eact same template and alias

directory structure.

The !/+/5command lists A*- dis% information. This command can run in two modes 4

connected and non$connected. 8n connected mode, A*-2-D uses the V$and GV$

views to retrieve dis% information. 8n non$connected mode, A*-2-D scans dis% headers

to retrieve dis% information, using an A*- dis% string to restrict the discovery set. The

connected mode is always attempted first.

ASMCMD ?+_a"523 -t?3-+&a"5230;0 & a+?+/51 & a/?+/5

ASMCMD ?+_r,/tor, t 2!! & a/?+/51 % a"523_%!,

ASMCMD !/+/5 5 DATA =_0001

ad bloc% repair is a new feature that runs automatically on normal or high redundancy

dis% groups. >hen a normal read from an A*- dis% group fails with an 8O error, A*-

attempts to repair that bloc% by reading from the mirror copy and write to it and by


39/44

relocating it if the copy failed to produce a good read. This whole process happens

automatically only on bloc%s that are read.

8t is possible that some bloc%s and etents on an A*- dis% group are seldom read.

One prime eample is the secondary etents. The A*-2-D?s repair command is

designed to trigger a read on these etents, so the resulting failure in 8O can start the

automatic bloc% repair process. One can use the A*-2-D?s repair interface if the

storage array returns an error on a physical bloc%, then the A*-2-D repair can initiate a

read on that bloc% to trigger the repair.

A*- =ariable *i/e 0tents is an automated feature that enables A*- to support larger

file si/e while improving memory usage efficiency. An A*- file begins with an etent

e&ual to one A!.

As the file si/e increases, the etent si/e also increases to I A! and then to LG A! at a

predefined number of etents. The si/e of the etent map that defines a file can be

smaller by a factor of I and LG depending on the file si/e. The initial etent si/e is e&ual

to the allocation unit si/e and it increases by a factor of I and LG at predefined

thresholds.

5ewer etent pointers are needed to describe the file and less memory is re&uired to

manage the etent maps in the shared pool, which would have been prohibitive in large

file configurations. 0tent si/e can vary both across files and within files.

=ariable si/e etents also enable you to deploy Oracle databases using A*- storage that

are several hundred T even several + in si/e. The management of variable si/e

etents is completely automated and does not re&uire manual administration.

owever, eternal fragmentation may occur when a large number of non$contiguous

small data etents have been allocated and freed, and no additional contiguous large

etents are available. A defragmentation operation is integrated as part of the rebalance

operation. *o, as a DA, you always have the possibility to defragment your dis% group

by eecuting a rebalance operation.

A*- imposes some limits3

LF dis% groups in a storage system

1@,@@@ A*- dis%s in a storage system G petabyte maimum storage for each A*- dis%

G@ eabyte maimum storage for each storage system

1 million files for each dis% group

maimum files si/es depending on the redundancy type of the dis% groups used

A*- imposes a maimum file si/e of


40/44

1G@ + for eternal redundancy 4 the value is currently greater than the possible database file

si/e

GE + for normal redundancy

1H + for high redundancy

)uestion

>hat can the A*-2-D utility be used for

Options3

1. Altering A*- dis% groups

E. 2reating A*- dis% groups

F. *tarting up an A*- instance

G. =iewing and manipulating A*- files and directories

Ans'er

A*-2-D is a command line utility that can be used for viewing and manipulating

A*- files and directories.

Option 1 is incorrect. ou use ?@B$lus to issue ALTERcommands for A7 dis%

groups. ou must be a member of the SYSASM, SYSDBA, or SYSOPERroles to be

able to issue alter commands.

Option 2 is incorrect. A7 dis% groups can be created from the ?@ prompt using

?@B$lus. ou must be a member of the SYSASMor SYSDBAroles to be able toissue the create command.

Option ! is incorrect. 7embers of the SYSASM, SYSDBA, or SYSOPERroles can

start up or shut down an A7 from the ?@ prompt using ?@B$lus, not

A7C7(.

Option " is correct. The A7C7( command line utility can be used to view and

manipulate files and directories within A7 dis% groups. A7C7( can list the

contents of dis% groups, perform searches, create and remove directories, and

more.

ummar!

A*- storage does not eliminate any eisting database functionality. Cew files may be

created as A*- files, and eisting ones are administered in the old way or can be

migrated to A*-. A*- files are always spread across all the A*- dis%s in a dis% group.


41/44

9ou can remove a dis% from a dis% group by using the ALTER DISKGROUPand DROP

DISKcommands. 9ou can cancel a dis% drop operation by using the UNDROPcommand.

The MOUNTand DISMOUNToptions allow you to ma%e one or more dis% groups available

or unavailable to the database instances.

A*-2-D is a command line utility that you can use to view and manipulate files anddirectories within A*- dis% groups. A*-2-D can perform A*- metadata bac%up and

restore functionality. A*- =ariable *i/e 0tents is an automated feature that enables

A*- to support larger file si/e while improving memory usage efficiency.

Table of Contents

| To% of %age|


| 1. A- storage conce%ts|

| 2. ALTE8 commands|

| *. A-C-D utilit!|

| ummar!|

2opyright J E@@K *%ill*oft. All rights reserved.





Creating an A- :nstance and Dis( "rou%s

Learning objective

After completing this topic, you should be able to create an ASM instance and dis group

and use the ASM&MD to 'ie! dis group data.

E+ercise overvie'

8n this eercise, you?re re&uired to use D2A to create an A*- instance and configure

two dis% groups for the A*- instance. 9ou are also re&uired to use A*-2-D commands

to view and manage files stored in the A*- dis% groups.

This involves the following tas%s3
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42/44

creating an A*- instance

creating dis% groups

using A*-2-D

Tas( 1= Creating an A- instance

*tart the Database 2onfiguration Assistant and create an A*- instance. >hen prompted

to run the localconfig add script, minimi/e the D2A and open a new terminal window.

Type ;su; to switch to the root user and specify ;oracle; as the password. un the script

using the ;[email protected].@dbM1binlocalconfig add; command. eturn to

the D2A, confirm the *9* password is ;oracle; and start the A*- instance.

te%s list

:nstructions

1. Type +"aand press Enter

E. On the Database 2onfiguration Assistant 3 >elcome page, clic% ,e+t

F. On the Operations page, select Configure Automatic torage -anagementand clic% ,e+t

G. 2lic% O/and clic% the -inimi9eicon

H. Double$clic% the Terminalicon

L. Type /2and press Enterand type ora"!,and press Enter

K. Type -201-a33-ora"!,-3ro+2"t-11'1'0-+_1-%#-!o"a!"o#%& a++and press Enter

I. 2lic% the -inimi9eicon

N. 2lic% ,e+t, type ora"!,in the *9* password and 2onfirm *9* password tet boes and clic% ,e+t

1@. 2lic% O/

Tas( 2= Creating dis( grou%s

2onfigure two dis% groups called ;DATA; and ;5A.; *pecify that the DATA dis% group

uses four E.I raw slices $ raw1, rawE, rawF, and rawG $ and employs normal

redundancy. *pecify that the 5A dis% group uses four E.I slices $ rawH, rawL, rawK,

and rawI $ and employs eternal redundancy. 0nsure that both databases are mounted

and do not perform other D2A operations.

te%s list

:nstructions

1. On the A*- Dis% roups page, clic% Create ,e'

E. 8n the 2reate Dis% roup dialog bo, type DATAin the Dis% roup Came tet bo and press Enter

F. *elect the chec%boes for the ra'1, ra'2, ra'*, and ra'dis% paths in the *elect -ember Dis%s section and


43/44

te%s list

:nstructions

clic% O/

G. 2lic% Create ,e'

H. 8n the 2reate Dis% roup dialog bo, type )RAin the Dis% roup Came tet bo and select E+ternal

L. 2lic% the elect Allchec%bo to select the four dis% paths and clic% O/

K. 2lic% 6inish

I. On the Database 2onfiguration Assistant dialog bo, clic% ,o

Tas( *= >sing A-C-D

*tart A*-2-D and view the contents of the 'DATA dis% group using the command ;ls

'DATA7.; "ist the contents of the DATA58"0 directory using the command ;ls

'DATAO2"DATA58"0.; 2reate a new directory called :mw in the DATA dis% group

using the command ;m%dir 'DATA:mw.; Then use A*-2-D to bac% up A*- metadata

for the DATA dis% group using the command ;mdMbac%up $g data.;

te%s list

:nstructions

1. Type a/?"?+and press Enter

E. Type !/ (DATA-=and press Enter

F. Type ls (DATA-ORCL-DATA)ILEand press Enter

G. Type ?5+%r (DATA-?>and press Enter

H. Type ?+_a"523 & +ataand press Enter

Table of Contents

| To% of %age|


| E+ercise overvie'|

| Tas( 1= Creating an A- instance|

| Tas( 2= Creating dis( grou%s|

| Tas( *= >sing A-C-D|
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