High Availability & Disaster Recovery in Azure SQL
Oct 24, 2023 9:00 AM

High Availability & Disaster Recovery in Azure SQL

by HubSite 365 about John Savill's [MVP]

Principal Cloud Solutions Architect

Pro UserDatabasesLearning Selection

Maximize Azure SQL services with high availability, disaster recovery options, automatic failover groups and georeplication

John Savill's [MVP] YouTube video explores matters of High Availability (HA) and Disaster Recovery (DR) for Azure SQL Services. The video commences with an explanation on HA, followed by a deep dive into topics like Availability Zones, server and databases and disaster recovery. The video thoroughly discusses Automatic failover groups, Geo-replication, replication technology as well as ways to accomplish a failover process.

Aziotate the automatic failover mechanism is built into the Azure SQL Database service, ensuring the databases are always online and healthy, enabling it to achieve the published SLA. This service is uniform across all purchasing models and service tiers of Azure SQL Database. As the video explains, there are several recommended practices to maximize availability - enabling zone redundancy, incorporating retry logic, and utilizing maintenance windows among others.

However, even with high availability maintenance, there may be scenarios of span-entire-region outages that necessitate a disaster recovery initiation. The video provides detailed guides in preparing for such scenarios - recommending active georeplication to have a secondary database in a different Azure region, enabling auto-failover groups, matching the geo-secondary database's service tier with the primary's, and maintaining a proper scaling protocol for both primary and secondary database.

Another crucial aspect touched upon is ensuring data availability and prioritizing it over higher commit latency. This is achieved via asynchronous replication of data between primary and secondary regions, often by employing the sp_wait_for_database_copy_sync stored procedure right after a transaction commit.

One main takeaway is the importance of monitoring data recovery lag to ensure no loss of committed transactions. The video also recommends for the backup storage redundancy option to be set to Geo-redundant backup storage to enable easy geo-restore capability. Unfortunately, this option is not available in regions without a region pair.

Properly executing disaster recovery drills and having a well-documented recovery process is also emphasized. According to the video, prepping the secondary Azure SQL server to become the new primary in case of an outage is key. This includes identifying the new primary, finding ways to redirect users to it, defining firewall rules, creating necessary logins, and updating alert rules, among others.

For more information on Azure SQL Database services' operational plans, please feel free to check out Azure Analytics.

General Overview of Azure SQL Database Services High Availability and Disaster Recovery

Ensuring high availability and disaster recovery for Azure SQL Database services is a comprehensive process. By conducting frequent disaster recovery drills and maintaining a well-documented recovery process, the impact of an unlikely outage can be minimized. This also involves potentially redirecting users to a new primary server, setting firewall rules and identifying necessary logins. By proactively taking steps to maximize availability, organizations can ensure the smooth running of operations even during outages. In addition to that, constant monitoring, appropriate scaling and opting for Geo-redundant backup storage are also integral to an effective recovery strategy.

Read the full article Azure SQL High Availability and Disaster Recovery

Azure Analytics - High Availability & Disaster Recovery in Azure SQL SEO

Learn about Azure SQL High Availability and Disaster Recovery

The video in question explores the High Availability (HA) and Disaster Recovery (DR) options for Azure SQL services. By investing time in understanding HA and DR strategies, users can optimize the benefits of Azure SQL Database service, ensuring databases stay online and healthy.

Central to ensuring maximum availability of databases are several recommended configurations. These include enabling zone redundancy for the database or elastic pool, utilizing retry logic in the application, setting maintenance windows, and testing application fault resiliency by triggering a failover manually. As we evaluate the DR precautions, it's clear that instances of zone redundancy and retry logic might not always guarantee availability during large-scale outages spanning an entire region.

Indeed, even though Azure SQL Database generally upholds high availability, sometimes you may need to initiate a disaster recovery strategy manually. Recommendations in this regard extend from enabling active geo-replication and auto-failover groups, ensuring that the geo-secondary database matches the primary database in terms of service tier, compute tier and size, and observing a specific order when scaling up or down.

The importance of asynchronous replication of data between the primary and secondary regions is also underscored, as is the necessity of monitoring the lag concerning Recovery Point Objective (RPO). Configuring the backup storage redundancy option to Geo-redundant backup storage for using geo-restore capability is another crucial DR checklist item.

  • Preparation for recovery to another data region entails several steps, including identifying a server in another region to become the new primary server and deciding how to redirect users to this server.
  • Another important aspect is outlining the firewall rules necessary for users to access the new primary database and creating the logins needed in the master database on the new primary server.
  • Familiarizing oneself with the security aspects post disaster recovery and updating alert rules to map to the new primary is significant as well.

Upon successful completion of this video tutorial, the viewer should be well-equipped to Review Azure SQL Database disaster recovery guidance, understand the SLA for Azure SQL Database and use automated backups for recovery.

An important note is that learning doesn't stop here. It's encouraged to continuously explore more about active geo-replication, geo-restore, auto-failover groups, and zone-redundant databases. Reviews, feedback, and additional resources are all part of the learning process. You're not alone in this journey, be sure to take advantage of the resources available.

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