ASM Initialization Parameters: ASM_DISKSTRING,ASM_DISKGROUPS

ASM Initialization Parameters
Some of the important parameter in Oracle ASM are

asm_diskstring
This parameter limit the set of disks that Automatic Storage Management considers for discovery.

The parameters default value is NULL. This default causes ASM to find all of the disks in a platform-specific location to which it has read/write access.

This parameter is dynamic and can be modified while ASM is Up. You dont need to bounce the ASM instance. But You should not changing the diskstring to exclude those disk for which diskgroup is mounted.It will give error in that while modifying the parameter. It can be set in spfile or memory

*.asm_diskstring='/dev/disk*'

alter system set asm_diskstring='/dev/oradisk*','/var/oradisk*' scope=both;

asm_diskgroups

This parameter lists the names of disk groups that will be mounted by an ASM instance at startup, or when the ALTER DISKGROUP ALL MOUNT statement is issued.

The parameters default value is NULL. If this parameter is not specified, then no disk groups are mounted
This parameter is dynamic and can be modified while ASM is Up. You dont need to bounce the ASM instance

*.asm_diskgroups='DATA','FLASH'

alter system set asm_diskgroups='DATA' scope =both;

asm_power_limit

This parameter decides the rebalancing power of the ASM instance. Suppose you add a disk and want to complete the rebalance in less time. Then you can increase this parameter

This is dynamic and can be modified in run time and does not require ASM bounce

*.asm_power_limit=10

alter system set asm_power_limit=2 scope=both;

instance_type

The INSTANCE_TYPE initialization parameter specifies whether the instance is a database instance, an Oracle Automatic Storage Management (Oracle ASM) instance, or an Oracle ASM Proxy instance.

In addition to values asm and rdbms, INSTANCE_TYPE can be set to asmproxy in an Oracle Flex ASM configuration.

The following is an example of the INSTANCE_TYPE parameter in the initialization file:

*.instance_type='ASM'

Shared_pool_size

This parameter shared_pool_size determine the amount of memory required to manage the instance. If we are using Automatic memory management, we dont need to set it. The default values are generally suitable for most of the instance

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.

*.shared_pool_size=700M

db_cache_size

This parameter specifies the memory for db cache. This buffer cache stores metadata blocks. Default value are generally suitable

*.db_cache_size=50M

*.large_pool_size=50M
*.processes=100

Under Score parameter in ASM

select a.ksppinm "Parameter", c.ksppstvl "Instance Value"
from x$ksppi a, x$ksppcv b, x$ksppsv c
where a.indx = b.indx and a.indx = c.indx
and ksppinm like '%ASM%'

Hope you like this articles on ASM Initialization Parameters and how to modify and set them. If you have any questions while using them ,do let me know .I will try my best to solve it.

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