If you used hostnames when you were initially setting up clustering, then you would just change the IP address associated with the hostname(s) on your DNS server. If, however, you used IP addresses in the cluster setup, then depending on your version of the firmware, this can be either a single or a multiple-stepped process.
In v5.1.3.xxx firmware and above:
you can change the IP addresses of the units and all clustering settings will change automatically. To verify this go to the Basic->IP Configuration page, change the IP address and then check the Advanced->Clustering page to see if the addresses there were updated. If they did, then you are finished.
If the IP addresses did not change or if you have an earlier version of firmware, then you will need to use the following procedure:
- From the Advanced->Clustering page take the units off line. NOTE: the unit you have selected to be the master device can be left On-Line if desired (see item 6 below) so it can continue to process mail while you are re-configuring the IP addresses.
- From the Advanced->Clustering page, remove the Cluster Shared Secret from all units in the cluster and save the page(s).
- From the Advanced->Clustering page on each unit, click on the "trashcan" icon for the OTHER units in the cluster. All units in the cluster should now show only themselves listed in the Clustered Systems list.
- From the Basic->IP Configuration page of each unit, change the IP address to its new value and save the changes. This should log you out and restart the Barracuda services.
- When the login page returns, from the Advanced->Clustering page of each unit, enter and save the "Cluster Shared Secret." This should log you out of the units. NOTE: the IP address should now be updated on the Cluster page. If the updated value does not appear, please contact Barracuda Support to update this address from the command line.
- Pick one of the units to be the "Master Unit." Note its IP address.
- Login to the other units in the cluster, Go to their Advanced->Clustering page(s).
- For each of the other units in the cluster:
A. Enter the IP address of the "Master Unit" into the "Add System" field.
B. Click on the "Join Cluster" button.
C. Finally, from the Basic->Administration page, set the unit back online (the online status can be toggled via buttons at the bottom of the page).
Note that you can contact Barracuda Technical Support to manually update the Cluster setting from the device's backend command line interface. This results in no downtime and can usually be done in a few minutes.