In this Document

APPLIES TO:

GOAL

The purpose of this note is to describe how to change or update the private network (cluster_interconnect) information in Oracle Clusterware. 

It may be necessary to change or update interface names, or subnet associated with an interface if there is a network change affecting the servers, or if the original information that was input during the installation was incorrect.   It may also be the case that for some reason, the Oracle Interface Configuration Assistant  ('oifcfg')  did not succeed during the installation.

Please refer to Note 276434.1 for modifying public network and VIP associated information
and refer to Note 1386709.1 for basics of IPv4 subnet and Oracle Clusterware.

SOLUTION

Network information(interface, subnet and role of each interface) for Oracle Clusterware is managed by 'oifcfg', but actual IP address for each interfaces are not, 'oifcfg' can not update IP address information. 'oifcfg getif' can be used to find out currently configured interfaces in OCR:

On Unix/Linux systems, the interface names are generally assigned by the OS, and standard names vary by platform. For Windows systems, see additional notes below. Above example shows currently interface eth0 is used for public with subnet 10.2.156.0, and eth1 for cluster_interconnect/private with subnet 192.168.0.0.

The 'public' network is for database client communication (VIP also uses the same network though it's stored in OCR as separate entry), whereas the 'cluster_interconnect' network is for RDBMS/ASM cache fusion. Starting with 11gR2, cluster_interconnect is also used for clusterware heartbeats - this is significant change compare to prior release as pre-11gR2 uses the private nodename that were specified at installation time for clusterware heartbeats.

If the subnet or interface name for 'cluster_interconnect' interface is incorrect, it needs to be changed as crs/grid user.

Case I. Changing private hostname

In pre-11.2 Oracle Clusterware, private hostname is recorded in OCR, it can not be updated. Generally private hostname is not required to change. Its associated IP can be changed. The only way to change private hostname is by deleting/adding nodes, or reinstall Oracle Clusterware.

In 11.2 Grid Infrastructure, private hostname is no longer recorded in OCR and there is no dependency on the private hostname. It can be changed freely in /etc/hosts.

Case II. Changing private IP only without changing network interface, subnet and netmask
              or changing private IP MAC address only without changing anything else

For example, private IP is changed from 192.168.1.10 to 192.168.1.21, network interface name and subnet remain the same, or MAC address is changed, private IP address/interface name/subnet/network all remain the same.

Simply shutdown Oracle Clusterware stack on the node where change required, make IP or MAC modification at OS layer as required (eg: /etc/hosts, OS network config etc) for private network, restart Oracle Clusterware stack will complete the task.

Case III. Changing private network MTU only

For example, private network MTU is changed from 1500 to 9000 (enable jumbo frame), network interface name and subnet remain the same.

1. Shutdown Oracle Clusterware stack on all nodes
2. Make the required network change of MTU size at OS network layer, ensure private network is available with the desired MTU size, ping with the desired MTU size works on all cluster nodes
3. Restart Oracle Clusterware stack on all nodes

Case IV. Changing private network interface name, subnet or netmask

When the netmask is changed, the associated subnet ID is often changed. Oracle only store network interface name and subnet ID in OCR, not the netmask. Oifcfg command can be used for such change, oifcfg commands only require to run on 1 of the cluster node, not all.

A. For pre-11gR2 Oracle Clusterware

1. Use oifcfg to add the new private network information, delete the old private network information:

2. Shutdown Oracle Clusterware stack

As root user: # crsctl stop crs

3. Make required network change at OS level, /etc/hosts file should be modified on all nodes to reflect the change.
Ensure the new network is available on all cluster nodes:

4. restart the Oracle Clusterware stack

As root user: # crsctl start crs

B. For 11gR2 Oracle Clusterware and 12c Cluster without Flex ASM

As of 11.2 Grid Infrastructure, the private network configuration is not only stored in OCR but also in the gpnp profile.  If the private network is not available or its definition is incorrect, the CRSD process will not start and any subsequent changes to the OCR will be impossible. Therefore care needs to be taken when making modifications to the configuration of the private network. It is important to perform the changes in the correct order. Please also note that manual modification of gpnp profile is not supported.

1. Ensure Oracle Clusterware is running on ALL cluster nodes in the cluster

2. As grid user:

Get the existing information. For example:

Add the new cluster_interconnect information:

Verify the change:

3. Shutdown Oracle Clusterware on all nodes and disable the Oracle Clusterware as root user:

4. Make the network configuration change at OS level as required, ensure the new interface is available on all nodes after the change.

5. Enable Oracle Clusterware and restart Oracle Clusterware on all nodes as root user:

6. Remove the old interface if required:

C. For 12c Oracle Clusterware with Flex ASM

Please review above section B and pay attention to the Note section, take a backup as follows:

1. Ensure Oracle Clusterware is running on ALL cluster nodes in the cluster

2. As grid user:

Get the existing information. For example:

Above example shows network eth0 is used for both cluster_interconnect and ASM network.

Add the new cluster_interconnect information:

 If different network is used for private network and ASM network, then modify them accordingly.

3. As ASMLISTENER is using the private network, modifying the private network will affect ASMLISTENER. It is required to add a new ASMLISTENER with the new network configuration. Skip this step if the subnet for the ASM network is not changed.

3.1. Add a new ASMLISTENER (for example: ASMNEWLSNR_ASM) with the new subnet, as grid user:

3.2. Drop the existing ASMLISTENER (ASMLSNR_ASM in this example) and remove the dependency, as grid user:

3.3 Verify the configuration

4. Shutdown Oracle Clusterware on ALL nodes and disable the Oracle Clusterware as root user:

5. Make the network configuration change at OS level as required, ensure the new interface is available on all nodes after the change.

6. Enable Oracle Clusterware and restart Oracle Clusterware on all nodes as root user:

7. Remove the old interface if required:

Something to note for 11gR2+

1. If underlying network configuration has been changed, but oifcfg has not been run to make the same change,  then upon Oracle Clusterware restart, the CRSD will not be able to start.

The crsd.log will show:

Above errors indicate a mismatch between OS setting (oifcfg iflist) and gpnp profile setting profile.xml.

Workaround: restore the OS network configuration back to the original status, start Oracle Clusterware. Then follow above steps to make the changes again. 

If the underlying network has not been changed, but oifcfg setif has been run with a wrong subnet address or interface name, same issue will happen.

2. If any one node is down in the cluster, oifcfg command will fail with error:

Workaround: start Oracle Clusterware on the node where it is not running. Ensure Oracle Clusterware is up on all cluster nodes. If the node is down for any OS reason, please remove the node from the cluster before performing private network change.

3. If a user other than Grid Infrastructure owner issues above command, it will fail with same error:

Workaround: ensure to login as Grid Infrastructure owner to perform such command.

4. From 11.2.0.2 onwards, if attempt to delete the last private interface (cluster_interconnect) without adding a new one first, following error will occur:

Workaround: Add new private interface first before deleting the old private interface.

5. If Oracle Clusterware is down on the node, the following error is expected:

Workaround: Start the Oracle Clusterware on the node

Notes for Windows Systems

The syntax for changing the interfaces on Windows/RAC clusters is the same as on Unix/Linux, but the interface names will be slightly different. On Windows systems, the default names assigned to the interfaces are generally named such as:

Local Area Connection
Local Area Connection 1 
Local Area Connection 2

If using an interface name that has space in it, the name must be enclosed in quotes. Also, be aware that it is case sensitive.  For example, on Windows,  to set cluster_interconnect:

However, it is best practice on Windows to rename the interfaces to be more meaningful, such as renaming them to 'ocwpublic' and 'ocwprivate'.   If interface names are renamed after Oracle Clusterware is installed, then you will need to run 'oifcfg'  to add the new interface and delete the old one, as described above.

You can view the available interface names on each node by running the command:

This command must be run on each node to verify the interface names are defined the same.

Ramifications of Changing Interface Names Using oifcfg

For the Private interface, the database will use the interface stored in the OCR and defined as a 'cluster_interconnect' for cache fusion traffic.  The cluster_interconnect information is available at startup in the alert log, after the parameter listing - for example:

If this is incorrect, then instance is required to restart once the OCR entry is corrected. This applies to ASM instances and Database instances alike. On Windows systems, after shutting down the instance, it is also required to stop/restart the OracleService<SID> (or OracleASMService<ASMSID> before the OCR will be re-read.

Oifcfg Usage

To see the full options of oifcfg, simply type:

$ <CRS_HOME>/bin/oifcfg

Case V. Add or remove cluster_interconnect for 11gR2 and above with HAIP

1. To add another private network into existing cluster using HAIP, as grid user:

 Shutdown CRS on ALL nodes, then restart CRS on ALL nodes for HAIP to pick up the new interface. It is insufficient to restart CRS in rolling manner.

2. To remove a private network from a cluster with HAIP, as grid user:

HAIP will failover to the remaining interface and clusterware/database continue to function after the interface removal.

To remove the extra HAIP interface, it is required to shutdown CRS on ALL nodes, then restart CRS on ALL nodes. It is insufficient to restart CRS in rolling manner.

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REFERENCES