Types of ASM Filenames
1. Fully Qualified ASM Filenames (System Alias)
You use this fully qualified name for referencing
existing ASM files. Here’s the syntax of an ASM file using a
fully qualified filename:
+group/dbname/file_type/tag.file.incarnation
2. Numeric ASM Filenames
ASM derives numeric filenames from fully
qualified ASM filenames and uses them to refer to existing
files.
+group.file.incarnation
3. Alias ASM Filenames
You can use ASM alias files both when creating
new ASM files and when referring to existing files. Alias
ASM filenames mean that the files are not OMF-managed files. Thus,
Oracle won’t automatically remove these files when it does not have
any further need for them.
+dgroup1/myfiles/control_file1
+dgroup2/mydir/second.dbf
4. Incomplete ASM Filenames
You can use an incomplete ASM filename only
when creating files.
+dgroup1
+dgroup1(datafile)
Alias Filename Management - Creating Disk Group
Directories for Alias Filenames
You must create a directory structure to
support your alias filenaming conventions.
ALTER DISKGROUP
dgroup1 ADD DIRECTORY
'+dgroup1/mydir';
Using Templates with Aliases
dgroup(template_name)/alias
+dgroup1(spfile)/config1
Adding Aliases
You can add a filename alias or rename an existing
alias name, using the ADD ALIAS or RENAME ALIAS clause of the ALTER
DISKGROUP statement.
ALTER DISKGROUP
dgroup1 ADD ALIAS
'+dgroup1/mydir/second.dbf' FOR
'+dgroupA/sample/datafile/mytable.342.3'
You can retrieve created aliases using v$ASM_ALIAS.
The REFERENCE_INDEX column is usable only for entries that are
directory entries in the alias directory. For non-directory entries,
it equals to zero.
Dropping Files and Aliases from a Disk Group
ALTER DISKGROUP
dgroup1 DROP FILE
'+dgroup1/payroll/compensation.dbf'
ASM File Templates
Whenever you create a disk group, Oracle establishes
a set of initial system default templates for that disk group.
You can create your own template:
alter diskgroup
test_group1 add template
production attributes (mirror fine)
You cannot change a files’s attributes once you
create it using a certain template. If you wish to change an ASM
file’s attributes, you must use the RMAN to copy the file into a new
file with the attributes you want.
Database Instance Parameter Changes
Increase shared pool size based on the following
guidelines:
• For disk groups using external redundancy: Every
100 GB of space needs 1 MB of extra shared pool plus a fixed
amount of 2 MB of shared pool.
• For disk groups using normal redundancy: Every 50
GB of space needs 1 MB of extra shared pool plus a fixed amount of
4 MB of shared pool.
• For disk groups using high redundancy: Every 33 GB
of space needs 1 MB of extra shared pool plus a fixed amount of 6
MB of shared pool.
To obtain the current database storage size that is
either already on ASM or will be stored in ASM:
SELECT d+l+t
DB_SPACE
FROM
(SELECT SUM(bytes)/(1024*1024*1024) d
FROM v$datafile),
(SELECT SUM(bytes)/(1024*1024*1024) l
FROM v$logfile a, v$log b
WHERE a.group#=b.group#),
(SELECT SUM(bytes)/(1024*1024*1024) t
FROM v$tempfile
WHERE status='ONLINE')
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