Configuring Initialization Parameters for Oracle ASM
Instances
To install and
initially configure an Oracle ASM instance, use Oracle Universal Installer
(OUI) and Oracle ASM Configuration Assistant (ASMCA).
After an Oracle ASM
instance has been installed on a single-instance Oracle Database or in an
Oracle Real Application Clusters (Oracle RAC) environment, the final Oracle ASM
configuration can be performed. Only a few Oracle ASM-specific instance
initialization parameters must be configured. The default values are usually
sufficient.
Initialization Parameter Files for an Oracle ASM Instance
When installing Oracle ASM in an Oracle Restart
(standalone) configuration, Oracle Universal Installer (OUI) creates a separate
server parameter file (SPFILE) and password file for the Oracle ASM instance.
The ASM SPFILE is stored in a disk group during installation.
When installing Oracle ASM in a clustered Oracle ASM
environment, OUI creates a single, shared SPFILE for Oracle ASM in a disk
group.
When upgrading an Oracle ASM instance, if the ASM SPFILE was
originally in a shared file system, then the upgraded Oracle ASM instance
retains the SPFILE in the same location. If the original Oracle ASM instance
used a PFILE, after an upgrade the instance continues to use a PFILE.
You can use an SPFILE or a text-based initialization parameter
file (PFILE) as the Oracle ASM instance parameter file. If you use an SPFILE in
a clustered Oracle ASM environment, then you must place the SPFILE in a disk
group, on a shared raw device, or on a cluster file system. Oracle recommends
that the Oracle ASM SPFILE is placed in a disk group. You cannot use a new
alias created on an existing Oracle ASM SPFILE to start the Oracle ASM instance
If you do not use a shared Oracle Grid Infrastructure home, then
the Oracle ASM instance can use a PFILE. The same rules for file name, default
location, and search order that apply to database initialization parameter
files also apply to Oracle ASM initialization parameter files.
- The location of the
initialization parameter file specified in the Grid Plug and Play (GPnP)
profile
- If the location has not
been set in the GPnP profile, then the search order changes to:
- SPFILE in the Oracle ASM
instance home
For example, the SPFILE for Oracle ASM has the following
default path in the Oracle Grid Infrastructure home in a Linux environment:
$ORACLE_HOME/dbs/spfile+ASM.ora
- PFILE in the Oracle ASM
instance home
Note:
A PFILE or SPFILE is required if your configuration uses
non-default initialization parameters for the Oracle ASM instance.
You can administer Oracle ASM initialization parameter files
with SQL*Plus, Oracle Enterprise Manager, ASMCA, and ASMCMD commands.
You can back up, copy,
or move an Oracle ASM SPFILE with the ASMCMD spbackup, spcopy or spmove commands. For information about these ASMCMD commands,
see "spbackup", "spcopy", and "spmove".
You can also use the SQL CREATE SPFILE to create an Oracle ASM SPFILE when connected to the Oracle ASM
instance.
You can copy and move an Oracle ASM PFILE with the commands
available on the specific platform, such as cp for Linux.
After copying or moving an SPFILE or PFILE, you must restart the
instance with the SPFILE or PFILE in the new location to use that SPFILE or
PFILE.
If the COMPATIBLE.ASM disk group attribute is set to 11.2 or greater for a
disk group, you can create, copy, or move an Oracle ASM SPFILE into the disk
group.
For example, after upgrading an Oracle ASM instance from 11g
release 1 (11.1) to 11g release 2 (11.2), you could place the Oracle ASM
SPFILE in a disk group that has COMPATIBLE.ASM set to 11.2.
In the following steps, assume an Oracle ASM 11g release
2 (11.2) instance is using a PFILE stored in $ORACLE_HOME/dbs/asmspfile.ora. You can use the SQL CREATE SPFILE statement to create an SPFILE from a PFILE stored in a local or
shared file system. If a PFILE does not exist, then it could be created with
the SQL CREATE PFILE statement.
- Connect to the Oracle ASM
instance.
For example:
$ sqlplus / as sysasm
- Create an SPFILE in a disk
group that has COMPATIBLE.ASM set to 11.2 with the SQL CREATE SPFILE statement.
For example, create an Oracle ASM SPFILE from the existing PFILE.
SQL> CREATE SPFILE = '+DATA/asmspfile.ora'
FROM
PFILE = '$ORACLE_HOME/dbs/asmpfile.ora';
The CREATE SPFILE statement also updates the Grid Plug and Play (GPnP)
profile. You can check the location of the Oracle ASM SPFILE in the GPnP
profile with the ASMCMD spget command. See "spget".
- Restart the Oracle ASM
instance so that the instance reads the SPFILE in the new location.
Setting Oracle ASM Initialization Parameters
There
are several initialization parameters that you must set for an Oracle ASM
instance. You can set these parameters with Oracle ASM Configuration Assistant
(ASMCA). You can also set some parameters after database creation using Oracle Enterprise
Manager or SQL
ALTER SYSTEM or ALTER SESSION statements.
The
INSTANCE_TYPE initialization parameter is the only required parameter
in the Oracle ASM instance parameter file. The Oracle ASM* parameters use
suitable defaults for most environments. You cannot use parameters with names
that are prefixed with Oracle ASM* in database instance parameter files.
Some database initialization parameters are also valid
for an Oracle ASM instance initialization file. In general, Oracle ASM selects
the appropriate defaults for database parameters that are relevant to an Oracle
ASM instance.
Automatic Memory
Management for Oracle ASM
Automatic
memory management automatically manages the memory-related parameters for both
Oracle ASM and database instances with the
MEMORY_TARGET parameter. Automatic memory management is enabled by
default on an Oracle ASM instance, even when the MEMORY_TARGET parameter is not
explicitly set. The default value used for MEMORY_TARGET is acceptable for most environments. This is the only
parameter that you must set for complete Oracle ASM memory management. Oracle
strongly recommends that you use automatic memory management for Oracle ASM.
If you do not set a value for
MEMORY_TARGET, but you do set values
for other memory related parameters, Oracle internally calculates the optimum
value for MEMORY_TARGET
based on those memory parameter values. You can also increase MEMORY_TARGET dynamically, up to the
value of the MEMORY_MAX_TARGET
parameter, just as you can do for the database instance.
Although it is not recommended, you can disable automatic
memory management by either setting the value for
MEMORY_TARGET to 0 in the Oracle ASM parameter file or by running an ALTER SYSTEM SET MEMORY_TARGET=0 statement. When you disable automatic memory management,
Oracle reverts to auto shared memory management and automatic PGA memory
management. To revert to Oracle Database 10g release
2 (10.2) functionality to manually manage Oracle ASM SGA memory, also run the ALTER SYSTEM SET SGA_TARGET=0 statement. 
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