Adding ASM Disks



  1. Check current disk size in the diskgroup. This new added disk should be same size to ensures that all of the disks in a disk group have the same I/O load.
  2. Present the disk to OS.
  3. Partition the disk if necessary. (Do no create file system)
  4. Change the owner of the disk to oracle user with dba/oinstall group. You can use the use mknod or just directly use raw name.
  5. Use dbca or sql command to add the disk.
    5a. Using Command Line.
    SQL> select name, path, header_status from v$asm_disk; — check if the new disk can be seen by Oracle ASM with header status ‘CANDIDATE’
    If not, check again the permission then check your asm_diskstring parameter in ASM instance.
    SQL> alter diskgroup add disk ‘<NEW_DISK_LOCATION’;
    e.g alter diskgroup redo add disk ‘/dev/dbcluster/asm/redodg2’;
  • Check the rebalance status
    SQL> select * from v$asm_operation;


5b. Using DBCA (GUI)

  • run the dbca > select ‘Configure Automatic Storage Management’ > Enter sys password > Enter DiskgroupName, Select Redundancy, Select Disk > Click OK.
  • If you didn’t see the disk in the Create Disk Group screen, click ‘Change Disk Discovery Path..’ and add the location. e.g ‘/dev/dbcluster/asm/*’;


You can also use ASMCMD for adding disks to diskgroup.
After inserting the disk, check status of the disk at ASM level by issuing

ASMCMD [+] > lsdsk –candidate -p (11g R2 command,
2010/02/asmcmd-10g-11g.html#lsdsk for syntax)

Then add it to the diskgroup by using chdg command.
ASMCMD [+] > chdg