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Automatic Storage
Management (ASM) in the Oracle 10g database
ASM provides a
vertical integration of the file system and the
volume manager that is specifically built for Oracle
database files. Its key features and benefits are:
-
Stripes files
rather than logical volumes
-
Online disk
reconfiguration and dynamic rebalancing
-
Adjustable
rebalancing speed
-
Provides
redundancy on a file basis
-
Supports only
Oracle database files
-
Custer-aware
-
Automatically
installed
ASM instance do not
have a data dictionary and it is restricted to few
SQL commands and Dynamic Performance view. The
following are some example of SQL commands.
Commands:
SQL> STARTUP/SHUTDOWN
SQL> ALTER DISKGROUP
MOUNT/DISMOUNT
SQL> ALTER DISKGROUP
ONLINE/OFFLINE DISK
SQL> ALTER DISKGROUP
REBALANCE
SQL> ALTER DISKGROUP
CHECK
�
Views:
V$ASM_TEMPLATE
V$ASM_DISKGROUP
V$ASM_CLIENT
V$ASM_FILE
V$ASM_ALIAS
V$ASM_DISK
V$ASM_OPERATION
�
The following are
examples of creating and deleting disk groups.
Creating a diskgroup:
SQL> CREATE DISKGROUP
dgora1 NORMAL REDUNDANCY
FAILGROUP
controller1 DISK
�/dev/rdsk/c0t0d0s2� NAME mydisk SIZE 200G FORCE,
�/dev/rdsk/c0t1d0s2�,
�/dev/rdsk/c0t2d0s2�
FAILGROUP
controller2 DISK
�/dev/rdsk/c1t0d0s2�,
�/dev/rdsk/c1t1d0s2�,
�/dev/rdsk/c1t2d0s2�;
Dropping a diskgroup:
SQL> DROP DISKGROUP
dgora1 INCLUDING CONTENTS;
The following are
examples of how to add disks to an existing disk
group.
SQL> ALTER DISKGROUP
dgora1
ADD FAILGROUP controller1
�/dev/rdsk/c0t3d0s2� NAME
a5;
To remove a disk:
SQL> ALTER DISKGROUP
dgora1 DROP DISK a5;
To undo the removed
disk do the following SQL statement. This only works
if the status of drop is pending or the drop
function was not completed yet.
SQL> ALTER DISKGROUP
dgora1 UNDROP DISKS;
Hands_On # 1:
Assuming you started
your ASM instance.
$ ORACLE_SID=+ASM;
export ORACLE_SID
$ sqlplus /nolog
SQL> CONNECT / AS SYSDBA
SQL> STARTUP
Display a list of your
diskgroups.
SQL> SELECT name FROM
v$asm_diskgroup;
Display a list of
associated ASM disks.
SQL> COL name FORMAT a20
SQL> COL failgroup
FORMAT a20
SQL> SELECT name,
failgroup, bytes_read, bytes_written
FROM
v$asm_disk
/
Display a list of
associated ASM files.
SQL> SELECT
group_number, file_number, bytes, type, striped
FROM
v$asm_file
/
Open another session
with different instance:
$ ORACLE_SID=school;
export ORACLE_SID
$ $ sqlplus /nolog
SQL> CONNECT / AS SYSDBA
Display a list of all
your datafiles.
SQL> COL file_name
FORMAT a40
SQL> SELECT file_name,
tablespace_name
FROM
dba_data_files
/
Create a tablespace
that is stored in the ASM disk group dgora1.
SQL> CREATE TABLESPACE
mytablespace2
DATAFILE
�+dgora1� SIZE 100m
/
Display a list of all
your datafiles. What do see?
SQL> COL file_name
FORMAT a40
SQL> SELECT file_name,
tablespace_name
FROM
dba_data_files
/
Now, you should have
one more line.
Go back on your ASM
instance and display a list of associated ASM files.
SQL> SELECT
group_number, file_number, bytes, type, striped
FROM
v$asm_file
/
The result should be
different than before. You added one more datafile
to it.
Add one addition disk
to your system.
SQL> HOST dd
if=/dev/zero of=/u02/oradata/school/diska abs=1024k
count=200
SQL> SELECT name,
failgroup, bytes_read, bytes_written
FROM
v$asm_disk
/
SQL> ALTER DISKGROUP
dgora1
ADD DISK
�/u02/oradata/school/diska�
/
Execute the following
query until you get �no rows selected.�
SQL> SELECT operation,
est_minutes
FROM
v$asm_operation
/
Again, display a list
of associated ASM disks.
SQL> SELECT name,
failgroup, bytes_read, bytes_written
FROM
v$asm_disk
/
Now, you should see
one more disk was added to disk group. |
