Configure disaster recovery for high availability

Disaster is a sudden disruption of business functions caused by natural calamities or human caused events. Disasters affect data center operations, after which resources and the data lost at the disaster site must be fully rebuilt and restored. The loss of data or downtime in the data center is critical and collapses the business continuity.

The Citrix ADM 12.1 disaster recovery (DR) feature provides full system backup and recovery capabilities for Citrix ADM deployed in high availability mode. At the time of recovery, certificates, configuration files, and a complete backup of the database is available in the recovery site.

The following table describes the terms used while configuring disaster recovery in Citrix ADM.

Terms Description
Primary site (Data center A) The primary site has Citrix ADM nodes deployed in high availability mode.
Recovery site (Data center B) The recovery site has a disaster recovery node deployed in standalone mode. This node is in read-only mode and is not operational until the primary site is down.
Disaster recovery node The recovery node is a standalone node deployed in the recovery site. This node is made operational (to the new primary) in case a disaster hits the primary site and it is non-functional.

Note

For more information on port and protocol details, see Ports.

Disaster recovery workflow

The following image shows the disaster recovery workflow, the initial setup before disaster, and the workflow after the disaster.

Initial setup before disaster

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The image above shows the disaster recovery setup before disaster.

The primary site has Citrix ADM nodes deployed in the high availability mode. To learn more, see High availability deployment

The recovery site has a standalone Citrix ADM disaster recovery node deployed remotely. The disaster recovery node is in read-only mode and receives data from the primary node to create data backup. NetScaler instances in the recovery site are also discovered but, they do not have any traffic flowing through them. During the backup process, all data, files, and configurations are replicated on the disaster recovery node from the primary node.

Prerequisites

Before you set up the disaster recovery node, note the following the prerequisites:

  • To enable disaster recovery settings, the primary site must have Citrix ADM nodes configured in high availability mode.

  • The standalone deployment of Citrix ADM in the primary site does not support the disaster recovery feature.

Citrix recommends that you set CPU priority (in virtual machine properties) at the highest level to improve scheduling behaviour and network latency.

The following table lists the minimum requirements to configure the Disaster Recovery node:

Component Requirement
RAM 32 GB
  Note: The default value is 8 GB. Citrix recommends that you increase the default value to 32 GB for better performance.
Virtual CPU 8 CPUs
  Note: The default is 2 CPUs. Citrix recommends that you increase the default value to 8 CPUs for better performance.
Storage Space Citrix recommends using solid-state drive (SSD) technology for Citrix ADM deployments.The default value is 120 GB. Actual storage requirement depends on Citrix ADM sizing estimation.If your Citrix ADM storage requirement exceeds 120 GB, you have to attach an additional disk. Note: You can add only one additional disk.Citrix recommends you to estimate storage and attach additional disk at the time of initial deployment.For more information, see How to Attach an Additional Disk to Citrix ADM.
Virtual network interfaces 1
Throughput 1 Gbps or 100 Mbps
Hypervisor Versions
Citrix XenServer 6.2 and 6.5
VMware ESXi 5.5 and 6.0
Microsoft Hyper-V 2012 R2
Linux KVM Ubuntu and Fedora

First time disaster recovery setup

  • Deploy Citrix ADM in high availability mode

  • Deploy and register the Citrix ADM disaster recovery node

  • Enable and disable disaster recovery settings from the user interface

Deploy Citrix ADM in high availability mode

To set up disaster recovery settings, ensure that Citrix ADM is deployed in high availability mode. For information on deploying the Citrix ADM in high availability, see High availability deployment

Note

  • Citrix ADM deployed in high availability mode must be upgraded to Citrix ADM release version 12.1.

  • Floating IP address is mandatory to register disaster recovery node with the primary node.

Deploy and register the Citrix ADM disaster recovery node

To register the Citrix ADM disaster recovery node:

  1. Download the .xva image file from the Citrix download site and import it into your hypervisor.

  2. From the Console tab, configure NetScaler MAS with the initial network configurations.

    Note

    The disaster recovery node can be on a different subnet.

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  3. After the initial network configuration is complete, the system prompts for login. Log on using the following credentials – nsrecover/nsroot.

  4. To deploy the disaster recovery node, type /mps/deployment_type.py and press enter. The NetScaler MAS deployment configuration menu is displayed.

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  5. Select 2 to register disaster recovery node.

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  6. The console prompts for floating IP address of the high availability node and password. Enter the floating IP address and password.

  7. Enter the floating IP address and password to register the disaster recovery node to the primary node.

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    The disaster recovery node is now registered successfully.

    Note

    The disaster recovery node does not have a GUI.

Enable disaster recovery settings from the Citrix ADM GUI

After the disaster recovery node is registered successfully, you can enable the disaster recovery settings from the Citrix ADM primary site user interface.

  1. Navigate to System > System Administration > Disaster Recovery Settings.

  2. On the Configure Disaster Recovery Settings page, select Enable Disaster Recovery check box, and click Apply Settings.

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  3. A confirmation dialogue box is displayed. Click Yes to continue.

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    Note

    The time taken for system backup depends on the data size and the WAN (Wide Area Network) link speed.

    To disable the disaster recovery settings, clear the Enable Disaster Recovery check box and click Apply Settings.

    A confirmation dialogue box is displayed. Click Yes to continue.

    Important

    • It is the responsibility of the administrator to detect that a disaster has occurred on the primary site.

    • The disaster recovery workflow is not automated and is manually initiated by the administrator after the primary site goes down.

    • An administrator must manually initiate the process by executing a recovery script on the disaster recovery node at the recovery site.

Workflow after the disaster

When the primary site goes down after a disaster, the disaster recovery workflow must be initiated as follows:

  1. The administrator identifies that a disaster has struck the primary site and it is not operational.

    Note

    It is the responsibility of the administrator to detect that a disaster has occurred on the primary site.

  2. The recovery process is initiated by the administrator.

  3. The administrator must manually execute the following recovery script on the disaster recovery node (at the recovery site): /mps/scripts/pgsql/pgsql_restore_remote_backup.sh

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  4. Internally, NetScaler instances are automatically reconfigured to send the data to the disaster recovery node that has now become the new primary site.

    The following image shows that the disaster recovery workflow after the primary site is struck with a disaster.

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Post disaster recovery

After the disaster has occurred and the recovery script is initiated by the administrator, the DR site will now become the new primary site.

Important

  • If you have installed Citrix ADM 12.1.49.x or earlier releases, you will get a grace period of 30 days to contact Citrix to rehost the original license on the Citrix ADM (at the DR site).

  • For 12.1.50.x or later releases, the Citrix ADM license is automatically synchronized to the DR site (Not a requirement to contact Citrix for the license).

  • Pooled license for the DR site is supported from 12.1.50.x or later releases. If you have applied pooled licenses for the instances, then you need to manually reconfigure the instances to the DR site.

Configure disaster recovery for high availability