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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!|
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of *%ill*oft in the !nited *tates and certain other countries.
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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
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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$distribute the files and maintain a
balanced 8O load across the dis%s in a dis% group.
>ith the 8O balanced whenever files are allocated and whenever the storage
configuration changes, the DA never needs to search for hot spots in a dis% group and
manually move data to restore a balanced 8O load. owever, because the databaseneeds to resync cached A*- metadata, rebalances will have less impact if done in &uiet
periods.
8t is more efficient to add or drop multiple dis%s at the same time so that they are
rebalanced as a single operation. This avoids unnecessary movement of data. >ith this
techni&ue, it is easy to achieve online migration of your data. All you need to do is add the
new dis%s in one operation and drop the old ones in one operation.
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9ou can control how much of a load the rebalance operation has on the system by setting
the ASM_POWER_LIMITparameter. 8ts range of values is 1 through 11. The lower the
number, the lighter the load 4 a higher setting has more of a load and finishes sooner.
ummar!
Automatic *torage -anagement (A*-# provides a vertical integration of the file system
and the volume manager that is specifically built for the Oracle database files.
To use A*-, you must start a special instance, called an A*- instance, before you start
your database instance. A*- instances manage the metadata needed to ma%e A*- files
available to ordinary database instances.
A dis% group is a collection of dis%s managed as a logical unit. *torage is added and
removed from dis% groups in units of A*- dis%s. A*- has three dis% group types that
support different types of mirroring 4 eternal$redundancy, normal$redundancy, and high$
redundancy.
Table of Contents
| To% of %age|
| Learning objective|
| 1. Automatic torage -anagement #A-$|
| 2. Creating an A- instance|
| *. A- dis( grou%s|
| ummar!|
2opyright J E@@L *%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.
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-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.
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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.
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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.
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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,
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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
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Var%a!, S%F, 9
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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
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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.
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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
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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
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| To% of %age|
| Learning objective|
| 1. -anaging dis( grou%s|
| 2. A- instances|
| ummar!|
2opyright J E@@L *%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.
| Print| Contents| Close|
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.
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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
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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
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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.
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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!
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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
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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
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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.
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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|
| Learning objective|
| 1. A- storage conce%ts|
| 2. ALTE8 commands|
| *. A-C-D utilit!|
| ummar!|
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of *%ill*oft in the !nited *tates and certain other countries.
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| Print| Contents| Close|
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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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
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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|
| Learning objective|
| E+ercise overvie'|
| Tas( 1= Creating an A- instance|
| Tas( 2= Creating dis( grou%s|
| Tas( *= >sing A-C-D|
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2opyright J E@@I *%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.