When starting up your ASM instance, you receive the following error:
SQL> startup pfile=$ORACLE_HOME/dbs/init+ASM.ora
ASM instance started
Total System Global Area 104611840 bytes
Fixed Size 1298220 bytes
Variable Size 78147796 bytes
ASM Cache 25165824 bytes
ORA-15032: not all alternations performed
ORA-15063: ASM discovered an insufficient number of disks for diskgroup “DGROUP3”
ORA-15063: ASM discovered an insufficient number of disks for diskgroup “DGROUP2”
ORA-15063: ASM discovered an insufficient number of disks for diskgroup “DGROUP1”
In trying to determine the cause of the problem, you issue this query:
SQL> show parameter asm
What is the cause of the error?
A.
The ASM_DISKGROUPS parameter is configured for three disk groups: DGROUP1,
DGROUP2, and DGROUP3.
The underlying disks for these disk groups have apparently been lost.
B.
The format of the ASM_DISKGROUPS parameter is incorrect. It should reference the disk
group numbers, not the names of the disk groups
C.
The ASM_POWER_LIMIT parameter is incorrectly set to 1. It should be set to the number
of disk groups being attached to the ASM instance.
D.
The ASM_DISKSTRING parameter is not set; therefore disk discovery is not possible.
E.
There is insufficient information to solve this problem.
Explanation:
ASM_DISKSTRING specifies an operating system-dependent value used by Automatic
Storage Management to limit the set of disks considered for discovery. When a new disk is
added to a disk group, each Automatic Storage Management instance that has the disk
group mounted must be able to discover the new disk using the value of
ASM_DISKSTRING.
In most cases, the default value will be sufficient. Using a more restrictive value may reduce
the time required for Automatic Storage Management to perform discovery, and thus
improve disk group mount time or the time for adding a disk to a disk group. A “?” at the
beginning of the string gets expanded to the Oracle home directory. Depending on the
operating system, wildcard characters can be used. It may be necessary to dynamically
change ASM_DISKSTRING before adding a disk so that the new disk will be discovered.
An attempt to dynamically modify ASM_DISKSTRING will be rejected and the old value
retained if the new value cannot be used to discover a disk that is in a disk group that is
already mounted.
Refer to here