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
  G_BACKUP_ASM1
  H_ASM1
  I_ASM1
  J_ASM1
  K_ASM1
• [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.