Monday, September 30, 2013

How to Remove ASM Diskgroups and ASM Instance

Information about How to Remove ASM Diskgroups and ASM Instance
This document will describe how to remove an ASM instance from a RAC node. It will also describe the entire process for removing ASM, removing ASM Diskgroups, and reinstalling ASM Instance.
This process is used to clean up a failed ASM install and wipe all ASM Instance/Diskgroups to prepare systems for a new ASM installation.

Document Creator Todd Walters

How to Remove ASM Instance and DiskGroups
  1. Check ASM status on RAC Nodes
    • Login via oracle and run showcrs  to view status.
  2. Stop ASM instance on each node:
    • srvctl stop asm -n node (where node is node name, ie srv0dbxd11)
  3. Login to node 2 and 3 and run . oraenv and source +ASMx where X=instance number, ie. +ASM2 for node2.
  4. Go to sqlplus with sqlplus sys as sysdba and do the following on node 2 & 3 first:
    • SQL> Alter diskgroup all dismount;
  5. Back on Node1, run sqlplus again and list all ASM Diskgroups with this command:
    • SQL> select name,total_mb from v$asm_diskgroup;
    • NAME                             TOTAL_MB
      ------------------------------ ----------
      DWAK_BACKUP_01                      40954
      DWAK_DATA_01                       225252
  6. To remove these ASM Diskgroups, complete the following command (Make sure you want to remove these)
    • SQL> drop diskgroup dwak_data_01 including contents;
    • Should see: Dropped dwakdb_data_01 successfully
    • Run drop command again for any other ASM diskgroups to remove.
  7. Next while logged in as Oracle on Node 1, remove all ASM instances
    • srvctl remove asm -n nodeX (where nodeX=srv0dbxd13 for example)
    • run for each node in RAC cluster.
  8. Next edit the /etc/oratab file on all nodes in RAC Cluster and remove the following line:
    • +ASM1:/u00/app/oracle/product/10.2.0/ASM:N  (remove this on all nodes)
  9. As root, verify all Oracle ASM disks are listed properly and run scandisks
    • [root@srv0dbxd11 init.d]# ./oracleasm listdisks
    • [root@srv0dbxd11 init.d]# ./oracleasm scandisks
      Scanning system for ASM disks:                             [  OK  ]
    • then run ./oracleasm restart to restart ASM
  10. Once everything is okay, you can reinstall ASM Instance.
    • Login to node 1 with VNC.
    • Run xhost +
    • su - oracle
    • . oraenv
    • +ASM1 and enter /u00/app/oracle/product/10.2.0/ASM for ORACLE_HOME
    • cd $ORACLE_HOME/bin and run ./dbca
    • choose Install ASM
    • Follow How to Install Oracle 10gR4 ASM Instance  guide.