High Availability SQL Cluster on Azure for Language School Chain in Vietnam

Success Stories

High Availability SQL Cluster on Azure for Language School Chain in Vietnam

Business Challenge

VUS is Vietnam-USA Society English Centers, a large Vietnamese chain of language learning centers with 20 years history. VUS operates 30 centers in Hanoi and Ho Chi Min City and employs over 650 administrators and teachers.

VUS had several SQL servers on-premises and needed to build high-availability always-on cluster in cloud. As a public cloud platform for the secondary site allocation the customer has chosen Azure. The primary objective included:

  • Building a new reliable Database Management System platform based on MS SQL Server;
  • Site resiliency and disaster recovery for SQL Server platform.


SQL Server Always On Availability Groups provide a unified high availability and disaster recovery (HADR) solution that improves upon legacy functionality previously found across disparate features. Prior to SQL Server 2012, several customers used database mirroring to provide local high availability within a data center, and log shipping for disaster recovery across a remote data center. With SQL Server 2012, this common design pattern can be replaced with an architecture that uses availability groups for both high availability and disaster recovery.

We propose to build the cluster in Azure with asynchronous availability group and leave synchronous availability group on-premises. It helps to build easy switched over cluster with two SQLs, then customer has extended this configuration to eight SQLs.

Moreover, we proposed to use the load balancer on Azure to orchestrate load flows during the peak periods. We helped customer to set up the policies for switching to cloud and back to on-premises infrastructure. After implementation we performed the failover tests to check how the cluster works.


Customer uses Azure part of infrastructure as primary and secondary site, making changes on their own. From time to time customer faces with network problems to which we respond with assessment and providing recommendations.

Since VUS has HA SQL Cluster its required databases are available for enterprise applications from all locations in two cities. Customer end-users mentioned that applications now don’t fail and teachers and students always have an access to required information.

We develop our relations with customer and propose our managed service to take the professional control and management for customer infrastructure in Azure.