Add or Replace Appliance or Node in a Cluster

This topic explains the prerequisites and procedure for adding and replacing an appliance or node to the cluster.

Adding Appliance or Node

The expansion of a multi-cluster involves adding nodes to enhance the capacity, performance, and resilience. Based on the existing cluster size, you can choose how many more nodes can be added to the cluster.

The following options are available:

• From 3-node to a 5-node cluster

• From 3-node to a 7-node cluster

• From 5-node to a 7-node cluster

• From 7-node to a 11-node cluster

  To move from 7-node to a 11-node cluster, you must first upgrade your HPE Aruba Networking Central On-Premises software to 2.5.8 version as 11-node cluster is supported only in HPE Aruba Networking Central On-Premises 2.5.8.

Nodes can be added to the cluster either using CLI Command-Line Interface. A console interface with a command line shell that allows users to execute text input as commands and convert these commands to appropriate functions. or HPE Aruba Networking Central On-Premises WebUI. For information how to Add and Replace a node using Command Line Interface, see Node Setup.

Important Notes

• In a 5-nodes cluster, additionally only 2-nodes can be added. Adding 4-nodes to a 5-nodes cluster will not work.

• 9-nodes cluster is not supported, in 7-nodes cluster, additionally only 4-nodes can be added. Adding 2-nodes to a 7-nodes cluster will not work.

Prerequisites

• The new node must have the same HPE Aruba Networking Central On-Premises software version, subnet, gateway, netmask, NTP Network Time Protocol. NTP is a protocol for synchronizing the clocks of computers over a network. , DNS Domain Name System. A DNS server functions as a phone book for the intranet and Internet users. It converts human-readable computer host names into IP addresses and IP addresses into host names. It stores several records for a domain name such as an address 'A' record, name server (NS), and mail exchanger (MX) records. The Address 'A' record is the most important record that is stored in a DNS server, because it provides the required IP address for a network peripheral or element. , and hardware and software requirements as other nodes in the cluster.

• Ensure permanent network configuration settings are done on the newly added nodes in the cluster. After the completion of prepare node operation, reboot the node.

To add a node or an appliance in the cluster, perform the following steps:

1. In the Appliance Resources table, click the icon at the top right corner.
   The Add Appliance Resource dialog box is displayed.

   The option is available for clusters that contain 3 or 5 appliances only. The option is unavailable in a setup that contains a single or seven devices.

2. Select the number of appliances to be added to the cluster along with corresponding FQDNs of the appliances.

   To add appliances to the cluster, you must add minimum of 2 appliance and maximum of 4 appliance.
   
   

3. Click Add.

   The nodes are added to the cluster.

Replacing Appliance or Node

Replacing a node is required if you encounter a faulty node in the cluster. You may want to replace an existing node to repair an existing host system that no longer functions or other various reasons.

The following methods are available for replacing nodes:

• Replace node using the same IP/FQDN Fully Qualified Location Name. FQLN is a device location identifier in the format: APname.Floor.Building.Campus.

• Replace node using different IP/FQDN

Prerequisite

• The new node must have the same HPE Aruba Networking Central On-Premises software version, subnet, gateway, netmask, NTP, DNS, and hardware and software requirements as other nodes in the cluster.

• If the IP address of the existing node is same, ensure that the node must be in Down state. If the node is not down, then that existing node must have HPE Aruba Networking Central On-Premises installed. After the replace operation with the new node is completed, bring up the old node using a different IP address.

• To perform the same node replace operation, the node that needs to be replaced must under go factory reset before proceeding with the replace.

To replace a node or an appliance in the cluster, perform the following steps:

1. In the Appliance Resources table, click the icon corresponding to the device.
   The Replace Appliance Resource dialog box is displayed.

2. Enter the FDQN of the new appliance and click Replace.

Important Points to Note

• HPE Aruba Networking Central On-Premises cluster WebUI cannot be accessed when add or replace node operation is in progress. It might approximately take 15 hours maximum to complete the operation (based on data size and upgrade history).

• Ensure to check if add or replace node operation was successful or failed on the System Operations page.

• If the HPE Aruba Networking Central On-Premises cluster is enabled with LAG Link Aggregation Group . A LAG combines a number of physical ports together to make a single high-bandwidth data path. LAGs can connect two switches to provide a higher-bandwidth connection to a public network. , after the add or replace node operation, ensure to enable LAG on the new node.

• During replace operation, if the node that is to be replaced is reachable, but you are unable to login to HPE Aruba Networking Central On-Premises for some reason such as, server reset or IP addresse being used elsewhere, then the replace operation fails. If the node is down or it is reachable and you are able to login to HPE Aruba Networking Central On-Premises, then replace operation works as usual.

Limitations

• The add or replace node operation is not supported on a single-node cluster.