Step-by-step guide on how to remove Oracle Real Application Clusters (RAC) from a Windows X64 system.

I had to remove Oracle 11g and reinstall Oracle 10gRel2 for a client recently.

1a, b and d are required if you are using RAW devices for your OCR and Votedisk If you are using OCFS for these files, skip to step 1c followed by 1e.

1. Remove the partitions that have been initialized for ocrcfg and votedsk

b. Stop windows services on each cluster node and set them to manual. So if nodes reboot while you tidying up the services will not attempt to start all by themselves.

OracleCSService
OracleCRService
OracleEVMService

c. Delete the partition using that was created

d. It is advisable to remove and recreate your logical drives on top of extended partitions at this time
from Windows Disk Management.

2. Execute the Oracle Universal Installer to remove all software from the CRS home

3. Run the Oracle Universal Installer to remove the empty CRS home and clean up the inventory file

4. Remove Oracle binaries using Windows explorer (right mouse click delete), both the CRS home and the files located in

c:\program files\oracle

5. Be sure to check the registry for each cluster node be sure all oracle services have been removed from windows server:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet\Services KEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services and any others

Example Oracle Services that should not exist anymore

OracleCSService
OracleEVMService
OracleCRService
OracleObjectService
OracleClusterVolumeService
OraFenceService

6. Using Windows explorer, be sure %systemroot%\windows\system32\drivers\ocfs.sys, %systemroot%\windows\system32\drivers\orafencedrv.sys, %systemroot%\windows\system32\drivers\orafenceservice.sys are removed

7. Reboot all servers in your RAC configuration

Once the reboot has completed start the with Oracle Clusterware re-installation

For more details on all things Oracle see the Oracle Scripts page