Deconfiguring Oracle 11gR2 RAC

When you are to uninstall Oracle RAC you can use following commands on  each nodes.

log in as root user.

Please run the following command on each and ever node except the last node.
 perl $GRID_HOME/crs/install/rootcrs.pl -verbose -deconfig -force

perl $GRID_HOME/crs/install/rootcrs.pl -verbose -deconfig -force -lastnode


Then clear ASM disks from the local node (first node)

dd if=/dev/zero of =/dev/sdx1 bs=1024 count=100 (sdx1 assigend to null(zero)).

Delete the ASM disks
/etc/init.d /oracleasm deletedisk VOL1
/etc/init.d/oracleasm deletedisk VOL2
/etc/init.d/oracleasm deletedisk VOL3
/etc/init.d/oracleasm deletedisk VOL4

Then create new ASM disk group
/etc/init.d/oracleasm createdisk VOL1  /dev/iscsi/asm1/part1
/etc/init.d/oracleasm createdisk VOL2  /dev/iscsi/asm2/part1
/etc/init.d/oracleasm createdisk VOL3  /dev/iscsi/asm3/part1
/etc/init.d/oracleasm createdisk VOL4  /dev/iscsi/asm4/part1

run this command to  list disks
      /etc/init.d/oracleasm listdisks 

On other nodes
run  following commands

      /etc/init.d/oracleasm scandisks
      /etc/init.d/oracleasm listdisks

Now the disks and Server is clear for the next installation. :)


If you could not deconfigure the RAC using above cammand

Please try with this

rm /etc/oracle/*
rm -f /etc/init.d/init.cssd
rm -f /etc/init.d/init.crs
rm -f /etc/init.d/init.crsd
rm -f /etc/init.d/init.evmd
rm -f /etc/rc2.d/K96init.crs
rm -f /etc/rc2.d/S96init.crs
rm -f /etc/rc3.d/K96init.crs
rm -f /etc/rc3.d/S96init.crs
rm -f /etc/rc5.d/K96init.crs
rm -f /etc/rc5.d/S96init.crs
rm -Rf /etc/oracle/scls_scr
rm -f /etc/inittab.crs
cp /etc/inittab.orig /etc/inittab

Above command will remove the Cluster Registry Files manually.


Please do remeber to
  1. remove folders inside /u01/app/    oracle . oraInventory , 11.2.0

          rm -rf oracle oraInventory 11.2.0 

  2.remove /etc/oratab file
         
          rm /etc /oratab