SNHA26: What to do when quorum loss happens in AG?

Описание: In this presentation, we delve into the intricacies of quorum loss in SQL Server Availability Groups (AG).I will guide you through the critical steps and scenarios involved in managing quorum loss.

Chapters:
0:30 - Heartbeat communication in Windows failover cluster:
The part illustrates the heartbeat communication process between two networks, highlighting the flow of heartbeat messages between primary and secondary replicas.

1:22 - How Quorum Loss Happens
A detailed diagram explains the concept of quorum loss in a distributed database system, how it happens and emphasizing the flow of transaction logs and replication mechanisms.

2:00 - Real life example of quorum loss

7:45 - Bringing the Cluster Back Online.
The presentation provides a step-by-step guide on how to restore a SQL Server cluster, including logging into the primary node, starting the WSFC cluster with FixQuorum, and performing a manual failover with possible data loss.

11:27 - Real example of bringing the cluster back online after quorum loss

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Commands used:
Import-Module FailoverClusters
$node = "WIN-LACE78A5KKH"
Stop-ClusterNode -Name $node
Start-ClusterNode -Name $node -FixQuorum
(Get-ClusterNode $node).NodeWeight = 1
$nodes = Get-ClusterNode -Cluster $node
$nodes | Format-Table -property NodeName, State, NodeWeight