Product Documentation

Command Center Appliances in a High Availability Pair

Dec 18, 2015

A high availability (HA) deployment of two Citrix® Command Center™ appliances can provide uninterrupted management of network devices. You configure one appliance as the primary node and the other as the secondary node. The primary node manages the network devices while the secondary node acts as a passive node. The secondary node becomes primary and takes over if the original primary node fails for any reason.

The primary node updates its health status at predefined intervals in a database table. Also, at predefined intervals, the secondary node checks the database for the status of the primary node. If a health check fails, the secondary node rechecks the health a predefined number of times, after which it determines that the primary node is not functioning normally. The secondary node then takes over as the primary (a process called failover). After a failover, the original secondary is the primary node. After the administrator corrects the problem on the original primary appliance and restarts it, the original primary appliance becomes the secondary node.

Important: In an HA setup, the database on the primary node must be completely in sync with the database on the secondary node. To maintain synchronization, MySQL two-way replication is configured as part of the HA setup.

Prerequisites

A successful high availability setup depends on the following conditions:
  • Both the primary and the secondary appliances should be operational and have the same build of the Command Center software.
  • The primary and secondary appliances must have the same time stamps. This can be ensured by synchronizing both the appliances with the same NTP server and verifying that the synchronization between the appliances and NTP server is successful. This is important to ensure an accurate timeline for performance data in case of a failover.
  • Both the primary and secondary appliances should have unique Hostname values to avoid host name resolution conflicts.
  • Both the primary and secondary appliances should have the same login credentials for the root user account.

Configuring High Availability

The appliance from which the configuration is initiated is designated as the primary node. Any data on the appliance designated as the secondary node is lost. During HA configuration, a number of actions, such as shutting down the server, backing up the database, and running replication commands on both databases, run in the background. The script may take from a few seconds to a few minutes to complete, depending on the size of the data that needs to be pushed from the primary appliance to the secondary appliance.

To configure Command Center appliances in high availability mode by using the graphical user interface

  1. Logon to Command Center client and navigate to Administration > Operations.
  2. Under Operations, click Setup High Availability.
  3. Type the IP address of the secondary node and click OK.
    Note: The login credentials for the root user account on both appliances should be same.

To configure Command Center appliances in high availability mode using an SSH client

  1. On a workstation or laptop, open an SSH connection to the appliance by using an SSH client, such as PuTTY.
  2. Log on to the appliance to be designated as the primary node. In User Name and Password, type the administrator credentials of the secondary node. The defaults are root and public, respectively.
  3. Change directory to /opt/Citrix/Citrix_Command_Center/bin. Then, at the shell prompt, type:

    sh configure_cc_ha.sh <SEC_IP> <USER_NAME>

  4. When prompted, type the password.

Parameters for configuring Command Center appliances in an HA setup

SEC_IP
IP address of the secondary node.
USER_NAME
Authorized user name for the secondary node (Default is root.)
PASSWORD
Password for the secondary node (Default is public.)

Removing Command Center Appliances from an HA Setup

You can remove Command Center appliances from an HA setup to run them as independent servers. This involves stopping the servers, stopping MySQL replication, and changing the configuration. Configuration is initiated from the primary node.

To remove Command Center appliances from an HA setup

  1. On a workstation or laptop, open an SSH connection to the appliance by using an SSH client, such as PuTTY.
  2. Log on to the primary node. In User Name and Password, type the administrator credentials. The defaults are root and public, respectively.
  3. Change directory to /opt/Citrix/Citrix_Command_Center/bin. Then, at the shell prompt, type:

    sh break_cc_ha.sh <USER_NAME>

  4. When prompted, type the password.

Parameters for removing a Command Center appliance from an HA setup

USER_NAME
Authorized user name for the primary node (Default is root.)
PASSWORD
Password for the primary node (Default is public.)

Performing a Force Failover in a High Availability Setup

You might want to force a failover if, for example, you need to replace or upgrade the primary node. Force failover is always initiated from the primary node.

To perform a force failover by using graphical user interface

  1. In a Web browser, type the IP address of the Command Center appliance. For example: https://10.102.31.69:8443/
  2. Log on to the appliance to be designated as the primary node. In User Name and Password, type the administrator credentials. The defaults are root and public, respectively.
  3. In the Menu bar, click Administration. Under Operations, click Force Failover.
  4. In the confirmation window, click OK.
    Note: After you confirm, the appliance is shutdown. You have to log on using the IP address of the secondary appliance. To view the status and other details, refer the log file under the logs/forcefailover_cc_ha.log directory.

To perform a force failover on a primary node in an HA setup

  1. On a workstation or laptop, open an SSH connection to the appliance by using an SSH client, such as PuTTY.
  2. Log on to the appliance to be designated as the primary node. In User Name and Password, type the administrator credentials. The defaults are root and public, respectively.
  3. Change directory to /opt/Citrix/Citrix_Command_Center/bin. Then, at the shell prompt, type:

    sh forcefailover_cc_ha.sh <USER_NAME>

  4. When prompted, type the password.

Parameters for performing a force failover in an HA setup

USER_NAME
Authorized user name for the primary node (Default is root.)