Solution to the disk related errors / ASM Diskgroup for RAC
17 Nov 2011 Leave a Comment
in ASM/RAC, oracle Tags: ASM, crs rac sun cluster orcludlm ucmmd solaris 10, DISKGROUP, ORA-15014, ORA-15018, Ora-15018 Ora-15031 Ora-15014, ORA-15031, ORACLE, RAC
The main purpose of sharing this tech note is that the Oracle’s note in metalink on this particular error did not provide a solution to environment. (Disk Is not Discovered in ASM, Diskgroup Creation Fails with Ora-15018 Ora-15031 Ora-15014 [ID 431013.1])
While it seems simple to add and drop the disk online in an ASM environment, often, we encounter very many errors based on the cluster software, OS and the way the SAN is visible to cluster. Before going into the detail, the error and work around let me briefly touch base on the general ASM operation specifically when altering the disk group for those who are new to ASM (automatic storage management).
We can use the ALTER DISKGROUP statement to alter a ASMdisk group configuration. As we know, we can add, resize, or drop disks while the database remains online. Whenever possible, multiple operations in a single ALTER DISKGROUP statement are recommended.
ASM automatically rebalances when the configuration of a disk group changes. By default, the ALTER DISKGROUP statement does not wait until the operation is complete before returning. Query the V$ASM_OPERATION view to monitor the status of this operation.
We can use the REBALANCE WAIT clause if you want the ALTER DISKGROUP statement processing to wait until the rebalance operation is complete before returning. This is especially useful in scripts. The statement also accepts a REBALANCE NOWAIT clause that invokes the default behavior of conducting the rebalance operation asynchronously in the background.
Having familiarized with the syntaxes and concepts, lets see the below command and error. As a part of migrating the ASM to a new SAN storage and would like to add the new disks to the existing the ASM disk group and plan to drop the old disks. The operation can be done online in oracle 11G R1 onwards; we plan to do this offline as the environment is 10204.
In the ASM instance:
==============
alter diskgroup RAWDG01 add disk ‘/dev/did/rdsk/d21s6′;
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15031: disk specification ‘/dev/did/rdsk/d21s6′ matches no disks
ORA-15014: location ‘/dev/did/rdsk/d21s6′ is not in the discovery set
As per the metalink note above, the recommendation is to use ‘dd’ command at OS level to cleanse the prior contents or use FORCE.
Since we are using the new disks, there is no need to use dd and the following force command did not work for us.
With FORCE option:
====================
alter diskgroup RAWDG01 add disk ‘/dev/did/rdsk/d21s6′ force
ORA-15032: not all alterations performed
ORA-15031: disk specification ‘/dev/did/rdsk/d22s6′ matches no disks
ORA-15014: location ‘/dev/did/rdsk/d22s6′ is not in the discovery set
SQL> CREATE DISKGROUP RAWDG03 disk ‘/dev/did/rdsk/d22s6′ force;
CREATE DISKGROUP RAWDG03 disk ‘/dev/did/rdsk/d22s6′ force
*
ERROR at line 1:
ORA-15018: diskgroup cannot be created
ORA-15031: disk specification ‘/dev/did/rdsk/d22s6′ matches no disks
ORA-15014: location ‘/dev/did/rdsk/d22s6′ is not in the discovery set
After going through the hundreds of pages of ASM manuals, we come across a relevant parameter asm_dsikstring that is empty in our environment.
SQL> show parameter asm_diskstring;
NAME TYPE VALUE
———————————— ———– ——————————
asm_diskstring string
SQL> alter system set asm_diskstring = ‘/dev/rdsk*’;
alter system set asm_diskstring = ‘/dev/rdsk*’
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-15014: location ‘/dev/rdsk/c4t60060160829012004CBE135E05ADDE11d0s0′ is not
in the discovery set
ORA-15025: could not open disk ‘/dev/rdsk’
ORA-15056: additional error message
SVR4 Error: 13: Permission denied
Additional information: 42
Additional information: 109884796
Additional information: 107607288
SQL> alter system set asm_diskstring = ‘/dev/rdsk/*s0′ SID=’*';
System altered.
SQL> show parameter asm
NAME TYPE VALUE
———————————— ———– ——————————
asm_diskgroups string RAWDG01, RAWDG02
asm_diskstring string /dev/rdsk/*s0
asm_power_limit integer 1
SQL> alter diskgroup RAWDG01 add disk ‘/dev/did/rdsk/d21s6′;
Diskgroup altered.
SQL> select substr(name,1,10) name,substr(path,1,20) path, REDUNDANCY, TOTAL_MB, free_mb from V$ASM_DISK
2 /
NAME PATH REDUNDA TOTAL_MB FREE_MB
———- ——————– ——- ———- ———-
/dev/rdsk/c4t6006016 UNKNOWN 511 0
/dev/rdsk/c4t6006016 UNKNOWN 511 0
/dev/rdsk/c4t600144F UNKNOWN 511 0
/dev/rdsk/c4t600144F UNKNOWN 511 0
/dev/rdsk/c4t600144F UNKNOWN 204699 0
/dev/rdsk/c4t600144F UNKNOWN 102286 0
/dev/rdsk/c4t600144F UNKNOWN 519 0
/dev/did/rdsk/d23s6 UNKNOWN 519 0
/dev/did/rdsk/d22s6 UNKNOWN 102286 0
/dev/did/rdsk/d19s6 UNKNOWN 511 0
/dev/did/rdsk/d20s6 UNKNOWN 511 0
NAME PATH REDUNDA TOTAL_MB FREE_MB
———- ——————– ——- ———- ———-
RAWDG02_00 /dev/rdsk/c4t6006016 UNKNOWN 204788 141340
RAWDG01_00 /dev/rdsk/c4t6006016 UNKNOWN 102394 11609
RAWDG01_00 /dev/did/rdsk/d21s6 UNKNOWN 204699 194393
In conclusion, we are able to add the new disks to the existing disk group after setting up the asm_distring on both the nodes. The fact that prior disk groups are being added during installation and configuration of ASM indicates that, perhaps we do not need to set this parameter when doing via cluster install or dbca. However, it is imperative from the current experience that asm_diskstring must be specified for managing the ASM disk groups.
Hope this helps to folks working on the ASM/RAC environment.
