| Question: What are the parameters that govern ASM? I understand that there are ASM init.ora parameters and OS level ASM parameters that must be set. How do you set up the ASM parameters?
Answer: Oracle ASM offers these
initialization parameters. _asm_diskgroups, asm_diskstring, asm_power_limit __asm_preferred_read_failure_groups_
instance_type:_ _ This is normally set to instance_type=ASM, but the default is non-ASM where instance_type= rdbms.
db_unique_name: This is a global unique name for the database that has npounted the ASM diskgroups. The default for db_unique_name is +asm.
asm_power_limit: The asm_power_limit parameter is the maximum power for a rebalancing operation on an ASM instance, with powers ranging from 1 (low) to 11 (high). The higher the "power", the faster an ASM rebuild operation will occur.
asm_diskgroups: The asm_diskgroups parameter will list of disk groups that should be mounted by the ASM instance at startup time, or by the alter diskgroup all mount statement.
asm_diskstring: The asm_diskstring parameter the maximum number of disks that can be considered during an ASM disk discovery operation.
asm_preferred_read_failure_groups:
Viewing ASM configuration parameters
You can use the following query to view the internal ASM parameters:
select
a.ksppinm "Parameter|Name", 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%'
order by
a.ksppinm;
Hidden ASM parameters
We also see these hidden ASM parameters (which should not be changed with the consent of Oracle technical support: The hidden ASM parameters are for experts only.**
_asm_acd_chunks
_asm_allow_only_raw_disks
_asm_allow_resilver_corruption
_asm_ausize
_asm_blksize
_asm_compatibility
_asm_dbmsdg_nohdrchk
_asm_disk_repair_time
_asm_droptimeout
_asm_droptimeout
_asm_emulmax
_asm_emultimeout
_asm_kfdpevent
_asm_kfioevent
_asm_libraries
_asm_maxio
_asm_repairquantum
_asm_runtime_capability_volume_support
_asm_skip_resize_check
_asm_stripesize
_asm_stripewidth
_asm_wait_time
_asmlib_test
_asmsid
_lm_asm_enq_hashing
With each new release of Oracle new ASM parameters may be introduced, so be sure to consult your Oracle documentation for complete details.