Always on Availability group (AG) cluster in SQL Server

In this video, I am going to introduce the concepts of Always On availability groups that are central for configuring and managing this type of cluster.
At first, I will show you why AG is needed and created, how it functions at high level. Afterwards, we will dive more deeply into internals of AG and I will show you in very much detailed way how AG works internally.
If you are building, troubleshooting or trying to understand AG cluster you find this video very useful.
Chapters
0:00 - Introduction
0:38 - Why AG is needed?
1:46 - Important features and concepts of AG: primary/secondary replica, listener, WSFC, data sync etc.
10:37 - Synchronization commit modes: Asynchronous-commit and synchronous-commit
14:05 - Internals of AG
21:24 - Disaster recovery solution: Manual, automatic and forced manual failovers
31:27 - Summary
Useful documentations on building multi region and multi subnet AG cluster:
learn.microsoft.com/en-us/azu...
learn.microsoft.com/en-us/azu...
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[@user-zz5ql5rq6f]

Thanks for this. At last I understood AG. I have never seen this kind of detailed video for AG internals. This is very good channel for internals :)

[@umakantkesgire7720]

Very useful information. Thanks a lot 🙏

[@arslanov1886]

Most welcome 😊

[@amarcse06]

Good session mate..please make the videos of basic troubleshooting in AOAG..thank you 🙂

[@arslanov1886]

Sure mate. Thanks for suggestions

[@vijaymunavalli335]

cool explanation.. thanks!!🙂

[@arslanov1886]

Glad it was helpful!

[@riazkm9136]

when we create windows failover cluster for SQL AG, do we need to have quorum disk / file witness? what is the best practice for the same.

[@arslanov1886]

yes, you should create quorum witness as best practice. If you do not have quorum witness, there will be 50% probability that your whole cluster fails when one node goes down. Please refer below official doc:
learn.microsoft.com/en-us/azure-stack/hci/concepts/quorum#examples

[@riazkm9136]

@@arslanov1886thank you very much for the prompt and detailed reply. our environment is on a vxrail. what will be the best witness to use? will a file share witness created on a nas storage work. have you got any good videos for configuring the windows failover cluster. if yes, please share.

[@arslanov1886]

As long as you have a constant and stable network between your servers and witness, you can choose any type of witness. There are other small points. Please refer below:
learn.microsoft.com/en-us/windows-server/failover-clustering/manage-cluster-quorum#witness-configuration
Please make sure that the witness is in another server.
I do not have videoes but I would follow the below good docs:
Step 1
learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/failover-cluster-instance-prepare-vm?view=azuresql&tabs=single-subnet
Step 2
learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/failover-cluster-instance-azure-shared-disks-manually-configure?view=azuresql