Changing Hub Node to Leaf Node and Vice Versa

The flex cluster setup used here consists of two hub nodes. One of the nodes will be changed from hub node to leaf node and back to a hub node. The nodes are named rhel12c1 and rhel12c2.

Changing Hub Node to a Leaf Node
Node rhel12c1 will be changed from a hub node to a leaf node. The current role could listed with

[root@rhel12c1 oracle]# crsctl get node role config
Node 'rhel12c1' configured role is 'hub'

To change the role of the node run the following command. This must be run on the node that's undergoing the role change as root

[root@rhel12c1 grid]# crsctl set node role leaf
CRS-4408: Node 'rhel12c1' configured role successfully changed; restart Oracle High Availability Services for new role to take effect.

Restart the node after the role change command has been executed

# crsctl stop crs
# crsctl start crs -wait

Verify the node started as a leaf node.

[root@rhel12c1 grid]# crsctl get node role config
Node 'rhel12c1' configured role is 'leaf'

The cluster now consists of a hub node and a leaf node

[root@rhel12c2 grid]# crsctl get node role config -all
Node 'rhel12c1' configured role is 'leaf'
Node 'rhel12c2' configured role is 'hub'

The database instance that was running while the rhel12c1 was a hub node will no longer be active and is in a shutdown state

ora.rac12c1.db
      1        ONLINE  OFFLINE                               Instance Shutdown,STABLE
      2        ONLINE  ONLINE       rhel12c2                 Open,STABLE

There's no resources running on the leaf node.

[root@rhel12c1 grid]# crsctl stat res -t -c rhel12c1

Finally update inventory as follows. Run the update node list command on hub nodes listing all remaining hub nodes in the cluster_nodes option. In this case only rhel12c2 is the hub node.

[grid@rhel12c2 ~]$ $GI_HOME/oui/bin/runInstaller -updateNodeList ORACLE_HOME=/opt/app/12.1.0/grid2 "CLUSTER_NODES={rhel12c2}" -silent -local CRS=TRUE
Starting Oracle Universal Installer...

Checking swap space: must be greater than 500 MB.   Actual 4506 MB    Passed
The inventory pointer is located at /etc/oraInst.loc
'UpdateNodeList' was successful.

On the leaf node run the update node list containing only the leaf node in the cluster_nodes option.

[grid@rhel12c1 ~]$ $GI_HOME/oui/bin/runInstaller -updateNodeList ORACLE_HOME=/opt/app/12.1.0/grid2 "CLUSTER_NODES={rhel12c1}" -silent -local CRS=TRUE
Starting Oracle Universal Installer...

Checking swap space: must be greater than 500 MB.   Actual 5112 MB    Passed
The inventory pointer is located at /etc/oraInst.loc
'UpdateNodeList' was successful.

This conclude converting from hub node to leaf node.



Changing Leaf Node to a Hub Node
Leaf node created in the previous step will be changed back to a hub node in this place. The current node role is

[grid@rhel12c1 ~]$ crsctl get node role config
Node 'rhel12c1' configured role is 'leaf'

As root change the node role to hub node with

[root@rhel12c1 grid]# crsctl set node role hub
CRS-4408: Node 'rhel12c1' configured role successfully changed; restart Oracle High Availability Services for new role to take effect.

Stop the cluster stack on the node undergoing the role change

# crsctl stop crs

Configure the Oracle ASM Filter Driver by running the following as root

# crsctl stop crs

[root@rhel12c1 grid]# /opt/app/12.1.0/grid2/bin/asmcmd afd_configure
Connected to an idle instance.
AFD-627: AFD distribution files found.
AFD-636: Installing requested AFD software.
AFD-637: Loading installed AFD drivers.
AFD-9321: Creating udev for AFD.
AFD-9323: Creating module dependencies - this may take some time.
AFD-9154: Loading 'oracleafd.ko' driver.
AFD-649: Verifying AFD devices.
AFD-9156: Detecting control device '/dev/oracleafd/admin'.
AFD-638: AFD installation correctness verified.
Modifying resource dependencies - this may take some time.

If the node started as a leaf node then it may also require VIP to be configured on the node before changing to hub node. As this started off as a leaf node the VIP already exists and this step is not needed. Once the ASM driver is configured start cluster stack on the node and verify the node role

[root@rhel12c1 grid]# crsctl start crs -wait
[grid@rhel12c1 ~]$ crsctl get node role config
Node 'rhel12c1' configured role is 'hub'

Resources there were down when the role was in leaf node role will be up and running again now.

[root@rhel12c1 grid]# crsctl stat res -t -c rhel12c1
--------------------------------------------------------------------------------
Name           Target  State        Server                   State details
--------------------------------------------------------------------------------
Local Resources
--------------------------------------------------------------------------------
ora.ASMNET1LSNR_ASM.lsnr
               ONLINE  ONLINE       rhel12c1                 STABLE
ora.DATA.dg
               ONLINE  ONLINE       rhel12c1                 STABLE
ora.FRA.dg
               ONLINE  ONLINE       rhel12c1                 STABLE
ora.LISTENER.lsnr
               ONLINE  ONLINE       rhel12c1                 STABLE
ora.NEWCLUSTERDG.dg
               ONLINE  ONLINE       rhel12c1                 STABLE
ora.net1.network
               ONLINE  ONLINE       rhel12c1                 STABLE
ora.ons
               ONLINE  ONLINE       rhel12c1                 STABLE
--------------------------------------------------------------------------------
Cluster Resources
--------------------------------------------------------------------------------
ora.LISTENER_SCAN1.lsnr
      1        ONLINE  ONLINE       rhel12c1                 STABLE
ora.asm
      2        ONLINE  ONLINE       rhel12c1                 Started,STABLE
ora.rac12c1.db
      1        ONLINE  ONLINE       rhel12c1                 Open,STABLE
ora.rhel12c1.vip
      1        ONLINE  ONLINE       rhel12c1                 STABLE
ora.scan1.vip
      1        ONLINE  ONLINE       rhel12c1                 STABLE
--------------------------------------------------------------------------------

Run the inventory update specifying all hub nodes in the cluster_node option

$GI_HOME/oui/bin/runInstaller -updateNodeList ORACLE_HOME=/opt/app/12.1.0/grid2 "CLUSTER_NODES={rhel12c1,rhel12c2}" -silent -local CRS=TRUE

This conclude the changing leaf node to hub node.