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44 Chapter 1
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Using Oracle ASM
Configuring and Backing Up to an ASM Flash Recovery Area
The flash recovery area is a directory structure that centralizes Oracle backups in one
Oracle-defined backup structure (see Chapter 2 for more on the flash recovery area). You
define the flash recovery area by setting the
DB_ RECOVERY_FILE_DEST and DB_RECOVERY_
FILE_DEST_SIZE
parameters as required. Here is an example of using the alter system
command to point the flash recovery area to an ASM disk group.
alter system set db_recovery_file_dest=’+COOKED_DGROUP1’;
alter system set db_recovery_file_dest_size=4G;
Once these parameters have been set, RMAN backups will start using the flash recovery
area and ASM since the flash recovery area has been configured to use an ASM disk group.
Summary
In this chapter, we showed you how Automatic Storage Management (ASM) can reduce
or eliminate the headaches involved in managing the disk space for all Oracle file types,
including online and archived logs, RMAN backup sets, flashback logs, and even initializa-
tion parameter files (spfiles).
We reviewed the concepts related to a special type of instance called an ASM instance along
with the initialization parameters specific to an ASM instance. In addition, we described the
dynamic performance views that allow you to view the components of an ASM disk group
as well as to monitor the online rebalancing operations that occur when disks are added to
or removed from a disk group. Starting and stopping an ASM instance is similar to starting
and stopping a traditional database instance. Of course, other databases that use disk groups
within the ASM instance will not be available to users if the ASM instance is not available to
service disk group requests.
ASM filenames have a number of different formats and are used differently depending
on whether existing ASM files or new ASM files are being referenced. ASM templates are
used in conjunction with ASM filenames to ease the administration of ASM files.
Additionally, we reviewed ASM disk group architecture, showing how failure groups can
provide redundancy and performance benefits while eliminating the need for a third-party
logical volume manager. Dynamic disk group rebalancing automatically tunes I/O perfor-
mance when a disk is added or deleted from a disk group or a disk in a disk group fails.
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