Business Continuity: Business Continuity is an important part of any organization, where an organization provides uninterrupted services to its customers that helps them to grow business and generate delightful customer experience. For the business to run smoothly without any interruption, its backend servers should be always up and running to fulfill the incoming requests. Business Continuity refers to maintaining the continuity of all operations and processes or quickly resuming the operations after server failover or event of disruption due to fire, flood, or malicious attack by cybercriminals. What is High Availability and Disaster Recovery: High availability can be explained as a system that always fulfills incoming requests with minimal latency and Disaster Recovery is a process to get data resiliency in the system by making multiple copies of the database on remote servers. If Disaster Recovery plans are not there, then the business might lose crucial data which plays an important role in business like customer, invoice, payment, order detail for an eCommerce system. Think of a scenario, where a company loses all the essential data due to any disaster occurred in the database system then the company may get in huge loss and may never recover lost information. That's why no one can bear the loss of precious data where business totally depends on it. With the above understanding, we can figure out that Database Systems play an essential part in the organization, so it becomes very important to monitor and maintain the database system’s health and availability. There are many vendors who provide Database systems like Microsoft, Oracle, Teradata, Exasol and many more. Each of them provides exciting features suitable to their environment for maintaining data integrity, availability, and system durability. HA and DR with Microsoft SQL server: Microsoft provides a SQL Server database system, which is used for building Transactional data (OLTP) and Analytics data systems (OLAP). The product is bundled with bags of features that can help organizations to keep the system secure, durable, and scalable. Microsoft SQL Server comes with advanced features to sustain data integrity, durability, and availability for running key business applications and operations. Microsoft SQL Server is available in three versions:

• Standard Edition:
• Enterprise Edition
• Developer Edition

  SQL Server provides a vast number of features to achieve high availability and data disaster recovery solutions for databases. It depends on the business needs that which process to be used to handle Disaster Recovery and high availability for the system. (At what extent business can bear the application downtime and data loss if any disaster occurs in the system.) Below features can be used for HA (High Availability) and DR (Disaster Recovery)

• Failover clustering: this can be achieved by setting up multiple servers in cluster mode to minimize the downtime for the application. If one server goes down, then another server takes its place and fulfills the incoming request. (Helpful to get better HA.)
• Replication: Data Replication is used for copying the data and database objects to multiple remote servers. Data replication can be one-to-one, many-to-one, or one-to-many also it can be bi-directional where one or more distributors can publish data to one or more subscribers. The data migrating part can take place as always on the sync process or a scheduled process.
• Database Mirroring: Mirroring is used to create another single replica of principle database on another server to provide Disaster Recovery and High Availability. All the transactions performed on the principal server will be performed on a mirrored server with no delay and both servers always will be in sync.
• Log shipping: Log shipping is used to transfer transaction log from Primary server to remote server, primarily used for disaster recovery plans. Log shipping plans can be a part of replication, mirroring, and always on failover cluster set up.
• Back-up Restore: Back and Restore is the process used for a Disaster Recovery plan, where the system administrator takes a full backup of the database system with the scheduled job and restores the DB if any issues occur on the server.

Note: we can get the above features in SQL server standard and Enterprise edition and the latest version is SQL server 2019. Which one to USE (Conclusion): Which disaster recovery and business continuity solutions will be the best fit for the various resilience requirements of your organization? It totally depends on the type of business requirement and budgets. There are many different software and products which provide a full proof plan for HA and DR with them and provide expert’s guidance to implement the solution into the environment. Like Oracle, Microsoft and Teradata provide sub-products with Database systems for HA and DR implementation. ~~ The blog is contributed by SmartERP employee: Dharmendra Kumar References:

• Microsoft Database mirroring
• SQL Server replication: Overview of components and topography