Product Documentation

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 NetScaler MAS 12.1 disaster recovery (DR) feature provides full system backup and recovery capabilities for NetScaler MAS 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 NetScaler MAS.

Terms Description
Primary site (Data center A) The primary site has NetScaler MAS 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.

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 NetScaler MAS nodes deployed in the high availability mode. To learn more, see High availability deployment

The recovery site has a standalone NetScaler MAS 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 NetScaler MAS nodes configured in high availability mode.
  • The standalone deployment of NetScaler MAS 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 for the virtual computing resources:

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 NetScaler MAS deployments.The default value is 120 GB. Actual storage requirement depends on NetScaler MAS sizing estimation.If your NetScaler MAS 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 NetScaler MAS.
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

  • Deploying NetScaler MAS in high availability mode

  • Registering and deploying the NetScaler MAS disaster recovery node
  • Enabling and disabling disaster recovery settings from the user interface

Deploying NetScaler MAS in high availability mode

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

Note

  • NetScaler MAS deployed in high availability mode must be upgraded to NetScaler MAS release version 12.1.
  • Floating IP address is mandatory to register disaster recovery node with the primary node.

Registering and deploying the NetScaler MAS disaster recovery node

To register the NetScaler MAS 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 as shown in the following image.

    Note

    The disaster recovery node can be on a different subnet.

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  3. After the initial network configuration is completed, 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 as shown in the following image.

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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.

    Important

    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.

Enabling disaster recovery settings from the NetScaler MAS GUI

After the disaster recovery node is registered successfully, you can enable the disaster recovery settings from the NetScaler MAS 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 Recoverycheck box and click Apply Settings.

    A confirmation dialogue box is displayed. Click Yesto 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 process is complete, you will be given time of 30 days to get your original licenses from Citrix.

Important

Ensure that you contact Citrix to update your instances to their original licenses. If you fail to contact Citrix within 30 days, your original licenses expire and a new license will be required.

Configure disaster recovery for high availability