High Availability
  • Updated on 25 Feb 2019
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High Availability

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High availability of the SaaS solution has been taken care by Serverless360, where as in a private hosted solution, high availability needs to be ensured in the client’s environment.
Private hosted version of Serverless360 comprises of three components,

  • Web application
  • SQL database
  • Windows NT service

These three components can be made Highly Available by different means, this article is a guide to achieving the same.

Web Application

The UI and API of Serverless360 will be hosted in the IIS of the server at the time of the installation. To make this highly available, the UI/API component should be installed in more than one server. A Network Load Balancer need to be configured for these instances. The Load Balancer checks for the available instance among different instances and provides the available instance for the user.

SQL Database

Serverless360 needs a SQL database instance created at the time of installation. Making it as a clustered SQL instance will make it highly available.

Windows NT service

The Serverless360 Background Service plays a key role as it is responsible to fetch the status of Azure entities and to process configured activities. When the background service accidentally stops running, configured monitors will not work as expected and scheduled activities will not be fired. To prevent this problem, you could cluster the background Service using the Windows Failover clustering mechanism. To solve this problem and to make the Serverless360 background Service more robust, Serverless360 offers out of the box High Availability.

Achieving High Availability

To achieve High Availability (HA), you need to install the Serverless360 background service on multiple servers and point them to the same Serverless360 configuration database. The background service on each Serverless360 server will do regular health checks to make sure at least one of them is active. Only the active server will trigger alerts and notifications of the monitors and execute scheduled activities at periodic intervals. Serverless360 considers one of the servers to be the primary server, while it treats the other to be secondary.

Activating a Serverless360 background service
You can manually change a passive server to the active state by selecting it and clicking on the Activate button. Instantly, the passive server becomes active and switches to be the primary server

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Viewing High Availability status

  1. Log in to the Serverless360 application
  2. Click 'Settings' (gear icon) located at the bottom of the page
  3. Click High Availability Status

If your environment has multiple registered servers, you will notice that one server is Active (primary) and the other one(s) are secondary

Active - Selecting and clicking the Activate button will activate the selected service (primary) and switch the remaining ones to secondary mode

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