Oracle 11g:Automatic Storage Management

Automatic Storage Management (ASM) provides a centralized way to manage Oracle Database disk storage.In this,we will discuss what ASM is, how to configure an ASM instance, how to manage an ASM instance, and finally, how to use ASM from within an Oracle database.

What is ASM?

  • ASM is designed to simplify Oracle database storage administration. Database environments have become  more complex, with large numbers of (and larger) data files,storage area networks (SANs), and high-availability requirements.
  • ASM is somewhat like a logical volume manager, allowing you to reduce the management of Oracle files into ASM disk groups. It also provides redundancy configurations, re-balancing operations, and, when installed on top of cluster ware, the ability to share database-related files.
  • ASM stores files in disk groups, which are logical entities made up of one or more physical disk drives. ASM is good for more than just storing database datafiles.
  • In an ASM instance, you can store database datafiles, online redo logs, archived redo logs, backup files, and data-pump dump files as well as change-tracking files and control files of one or several Oracle databases, though these databases and the ASM instance must have affinity to a given machine or cluster.
  • ASM also provides the ability to locate the flash recovery area on an ASM disk group, so your backups to disk can be made to ASM.

Features of ASM

Creating the ASM Instance

To create the ASM instance with the DBCA, do the following:

from SQL*Plus, as shown in this example:

C:\Documents and Settings\technooracle>Set ORACLE_SID=+ASM

C:\Documents and Settings\technooracle>Sqlplus sys/Robert as sysasm

SQL*Plus: Release 11.1.0.6.0 – Production on Mon Jul 14 19:55:33 2008

Copyright (c) 1982, 2007, Oracle. All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 – Production

With the Partitioning, OLAP and Data Mining options

SQL> select instance_name from v$instance;

INSTANCE_NAME

—————-

+asm

Starting and Stopping the ASM Instance

Starting an ASM Instance

Starting an ASM instance is quite easy, as shown in this exercise.

1. The name of the resulting instance will be +ASM. You can log into the ASM instance

2. Now, start the ASM instance with the startup command:

SQL> startup

ASM instance started

Total System Global Area 83886080 bytes

Fixed Size 1247420 bytes

Variable Size 57472836 bytes

ASM Cache 25165824 bytes

Shutting down the ASM instance is just as easy. A shutdown immediate, shutdown abort, or just a plain shutdown will do fine. If you execute a normal or immediate shutdown command on an ASM instance, that shutdown will fail if there is any database using that ASM instance. An error will be returned and the ASM instance will stay up. As a result, before you shut down the ASM instance, you will need to shut down all databases using that ASM instance.
You can perform a shutdown abort on the ASM instance. This will cause the ASM instance to shut down immediately and all of the associated databases will be shut down in an inconsistent state. This will require instance recovery when the databases are restarted, which can increase the time it takes to reopen the database. Oracle recommends that you not use the shutdown abort command when stopping an ASM instance.

The options for the STARTUP command are:

The options for the SHUTDOWN command are:

What is supported in ASM

Only Oracle files are supported:

* Database files
* Control files
* Online redo log files
* Archived redo log files
* Flash recovery area files
* RMAN files (image copy and backup)

These files are NOT supported:

* Installation files (in ORACLE_HOME, CRS_HOME)
* ORACLE_BASE files( including alert log, trace files, etc)
* CRS voting disk and OCR files
* Output data from UTL_FILE
* Any user or application specific files(e.g. XML or Java files)
* Oracle 9i external table files

Written by admin on January 1st, 2011 with comments disabled.
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