Book Image

Professional SQL Server High Availability and Disaster Recovery

By : Gethyn Ellis
5 (1)
Book Image

Professional SQL Server High Availability and Disaster Recovery

5 (1)
By: Gethyn Ellis

Overview of this book

Business continuity is of utmost importance. High availability (HA) and disaster recovery (DR) ensure that your infrastructure experiences no downtime and smoothly functions at all times. Sound knowledge of various HA and DR techniques help you to drastically reduce the downtime of your applications. This course begins by explaining the high availability and disaster recovery technologies available in SQL Server: Replication, AlwaysOn, and Log Shipping. You’ll learn what they are, how to monitor them, and how to troubleshoot any related problems. You’ll learn how to use different HA and DR topologies to create a highly available infrastructure that also includes hybrid topologies. You’ll learn what is Always On, it’s pros and cons, prerequisites, and restrictions. You’ll also learn about log shipping, one of the oldest SQL Server solutions, which is mostly used for DR and SQL Server migration. Through this course, you will be able to explore the technical implementations of high availability and disaster recovery technologies that you can use when you create a highly available infrastructure, including hybrid topologies. By the end of the course, you’ll feel confident and look forward to changing the game with robust and high performing infrastructure.
Table of Contents (7 chapters)
Chapter 4
AlwaysOn Availability Group
Content Locked
Section 3
Data Synchronization
In synchronous commit mode, a transaction takes a longer time to complete as it has to be committed at primary and secondary replicas. A synchronous commit, however, ensures zero data loss. The primary and secondary replicas always ping each other to check connectivity. If there's a delay of more than 10 seconds in receiving a response, the synchronous replica mode changes to asynchronous. The mode is restored back to synchronous once the connectivity is restored Here you will learn about the following: - Synchronous Commit - Asynchronous Commit - Primary Replica Fails - Planned - Forced and, - Automatic - Secondary Replica Fails