The function and function of ASM Buffer cache in Oracle

10g in view v$sga_dynamic_components we notice a component:asm Buffer Cache, and in the Instance_type=asm instance, the parameter has a value. That is, the parameter is used for ASM instances, it is used to do what, in the doc searched for a while did not find, I guess should be similar to the role of Db_cache_size, estimated to be used to cache disk header information.

Sql> select Component,current_size from v$sga_dynamic_components;

COMPONENT current_size

------------------------------ ------------

Shared Pool 41943040

Large Pool 12582912

Java Pool 0

Streams Pool 0

DEFAULT Buffer Cache 0

KEEP Buffer Cache 0

Recycle buffer Cache 0

DEFAULT 2K Buffer Cache 0

DEFAULT 4K Buffer Cache 0

DEFAULT 8K Buffer Cache 0

DEFAULT 16K Buffer Cache 0

COMPONENT current_size

------------------------------ ------------

DEFAULT 32K Buffer Cache 0

ASM Buffer Cache 25165824

Rows selected.

Sql> alter system set sga_target=80m;

Alter system set sga_target=80m

*

ERROR at line 1:

Ora-15021:parameter "Sga_target" isn't valid in ASM instance

--accidentally found Sga_target not suitable for ASM instance types

Sql> Show Parameter Instance_type

NAME TYPE VALUE

---------------------------------------------------------

Instance_type string asm

Sql>

Author: 51cto Blog Oracle Little Bastard

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