Automatic Storage Management Compatibility


Applies to : Database Management Software Oracle 11g R1 to Oracle 11g R2

Automatic Storage Management introduce two new parameters in Oracle 11g R1. These parameters introduced are for disk groups mounted on Automatic Storage Management instances. Before that, just to notify there is no compatible like init parameter in Automatic Storage Management as it used to be in Database Instance.

Compatible.asm: The minimum version of the ASM software that can access the disk group. In 11g, the default setting is 10.1.

E.g. Suppose you have a disk group with Compatible.asm parameter set to 11.1 and you have another ASM instance with version 10.2. So, you can't access this disk group.

In contrast, if you have a disk group with Compatible.asm parameter set to 11.1 and another ASM instance with version 11.2. So, you can access this disk group.

Though, I have not seen so many situations like this, but for sure there are few new feature in Database Management Software Oracle 11g R2 for which Compatible.asm must set to 11.2 like

Automatic Storage Management Dynamic Volume Striping.
Automatic Storage Management ACL's
Automatic Storage Management intelligent data Placement.

compatible.rdbms: The value for the disk group COMPATIBLE.RDBMS attribute determines the minimum COMPATIBLE database initialization parameter setting for any database instance that is allowed to use the disk group.

For example, if the COMPATIBLE initialization parameters of the databases are set to either 11.1 or 11.2, then COMPATIBLE.RDBMS can be set to any value between 10.1 and 11.1 inclusively.

In conclusion,  COMPATIBLE.RDBMS value should always be greater than COMPATIBLE initialization parameters of database Instance.

Whenever an Automatic Storage Management (ASM) disk group is created it's compatibility is set to 10.1.0.0.0 irrespective of current version of database.

Command to Check Compatible parameter values:

sql> select name, compatibility, database_compatibility from v$asm_diskgroup;

NAME COMPATIBILITY DATABASE_C
---------------------------------
DG1 10.1.0.0.0 10.1.0.0.0

However, To use any new feature of Automatic Storage Management, we needs to be upgraded compatibility parameters.

Command to update compatibility parameters:

sql> ALTER DISKGROUP dg1 SET ATTRIBUTE 'compatible.asm'='11.1';
Diskgroup altered.

sql> ALTER DISKGROUP dg1 SET ATTRIBUTE 'compatible.rdbms'='11.1';
Diskgroup altered.

sql> select name, compatibility, database_compatibility from v$asm_diskgroup;

NAME COMPATIBILITY DATABASE_C
---------------------------------
DG1 11.1.0.0.0 11.1.0.0.0

2 comments:

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