Using Failover Manager with Virtual IP Addresses v4.1
Failover Manager uses the
efm_address script to assign or release a virtual IP address.
Virtual IP addresses are not supported by many cloud providers. In those environments, another mechanism should be used (such as an Elastic IP Address on AWS), which can be changed when needed by a fencing or post-promotion script.
By default, the script resides in:
Failover Manager uses the following command variations to assign or release an IPv4 or IPv6 IP address.
To assign a virtual IPv4 IP address:
To assign a virtual IPv6 IP address:
To release a virtual address:
<interface_name> matches the name specified in the
virtual.ip.interface property in the cluster properties file.
<IPv6_addr> matches the value specified in the
virtual.ip property in the cluster properties file.
prefix matches the value specified in the
virtual.ip.prefix property in the cluster properties file.
For more information about properties that describe a virtual IP address, see The Cluster Properties File.
You must invoke the
efm_address script as the root user. The
efm user is created during the installation, and is granted privileges in the sudoers file to run the
efm_address script. For more information about the sudoers file, see Extending Failover Manager Permissions.
If a VIP address (or any address other than the
bind.address) is assigned to a node, the operating system can choose the source address used when contacting the database. Be sure that you modify the
pg_hba.conf file on all monitored databases to allow contact from all addresses within your replication scenario.
Testing the VIP
When using a virtual IP (VIP) address with Failover Manager, it is important to test the VIP functionality manually before starting Failover manager. This will catch any network-related issues before they cause a problem during an actual failover. While testing the VIP, ensure that Failover Manager is not running.
The following steps test the actions that Failover Manager will take. The example uses the following property values:
virtual.ip.prefix specifies the number of significant bits in the virtual Ip address.
When instructed to ping the VIP from a node, use the command defined by the
- Ping the VIP from all nodes to confirm that the address is not already in use:
You should see 100% packet loss.
- Run the
efm_address add4command on the Primary node to assign the VIP and then confirm with ip address:
- Ping the VIP from the other nodes to verify that they can reach the VIP:
You should see no packet loss.
- Use the
efm_address delcommand to release the address on the primary node and confirm the node has been released with ip address:
The output from this step should not show an eth0 interface
- Repeat step 3, this time verifying that the Standby and Witness do not see the VIP in use:
You should see 100% packet loss. Repeat this step on all nodes.
- Repeat step 2 on all Standby nodes to assign the VIP to every node. You can ping the VIP from any node to verify that it is in use.
After the test steps above, release the VIP from any non-Primary node before attempting to start Failover Manager.
The network interface used for the VIP does not have to be the same interface used for the Failover Manager agent's
bind.address value. The primary agent will drop the VIP as needed during a failover, and Failover Manager will verify that the VIP is no longer available before promoting a standby. A failure of the bind address network will lead to primary isolation and failover.
If the VIP uses a different interface, you may encounter a timing condition where the rest of the cluster checks for a reachable VIP before the primary agent has dropped it. In this case, EFM will retry the VIP check for the number of seconds specified in the
node.timeout property to help ensure that a failover happens as expected.