Adding new Virtual IP (VIP) or logical host in oracle CRS (cluster ready service)

Oracle cluster ready service (CRS) allows you create VIP (virtual IP) during installation. In a typical Oracle RAC (real application cluster) setup, application server will use the VIP to connect to the database. If you have configured multiple network interface cards on the database servers, it becomes challenge to have more than one VIP accessible to RAC. Before we discuss about this, we need to understand WHY multiple VIPs are required.

Consider you have 4 network cards (eth0, eth1, eth2, eth3) installed on each node of a 4 node cluster (node1, node2, node3, node4). eth0 NIC (network interface card) is reserved for management activities like BAU monitoring or accessing the database server for DBA (database administrator) or system administrative task. This is to avoid the network load of live traffic i.e. minimal disruption on application server and database server connectivity. eth1 is reserved for live users.

This interface is hosting VIP configured during CRS installation. eth2 is used for cluster interconnect. Surely you do not want to hammer this NIC for management purpose. As we know running oracle rman database backup or archive backup sometimes can kill the network thus eth3 is configured for backup activity, separate from live user and cluster interconnect. In this article, we will be focusing on eth3. Imagine you are running rman backup via netbackup and the node configured for backup is not available due to hardware failure or some other reason. The backup will fail as it cannot reach to the cluster node. If we could configure a logical host or VIP for backup activity, it will allow backup to continue on other survivor node of the cluster hence you are taking full benefit of RAC/ high availability. In the event of node unavailability, VIP will failover to another surviving node and this will increase resilience.

How to configure new application VIP?

Pre-requirements

1. Setup the /etc/hosts file on all nodes of the cluster. The host file should contain the entery of Netbackup Servers and application VIP (orcl-bkup).
i.e.
# Oracle RAC Database Backup Logical Hosts
192.168.1.3  orcl-bkup # Application VIP
# Netbackup Entries
#
192.168.1.30   – netbkup-bk # Netbackup Server

2. Connectivity between database server and Netbackup server

3. CRS_HOME environment variable if you do not want to give full path

Creating Application VIP

1. Create the application VIP profile on the database server:
#crs_profile -create orcl-bkup \
-t application   \
-a $CRS_HOME/bin/usrvip  \
-o oi=eth3,ov=192.168.1.3,on=255.255.255.0

This creates a file in:

$CRS_HOME/crs/public/orcl-bkup.cap

If you modify the file you will need to re-register:
#crs_register orcl-bkup -u -dir $CRS_HOME/crs/public

2. Register the Application VIP
#crs_register orcl-bkup

If you modify the file you will need to re-register:
#crs_register orcl-bkup -u -dir $CRS_HOME/crs/public

3. Change the owner of the resource and allow oracle to execute the script

su root
crs_setperm orcl-bkup -o root
crs_setperm orcl-bkup -u user:oracle:r-x

4. Start the VIP

crs_start orcl-bkup [-c node_name]

Removing Application VIP

1. Stop the VIP

crs_stop orcl-bkup

2. Delete the Application VIP profile

crs_profile -delete orcl-bkup

3.            Unregister the application VIP

crs_unregister orcl-bkup