The speaker shares his background as a SQL Server DBA and the efficiency gains that led him to explore running stateful workloads in Kubernetes.
When a node fails, Kubernetes waits five minutes by default before rescheduling pods, which is too long for stateful applications like SQL Server.
A live demo shows an nginx pod taking five minutes to be rescheduled to a healthy node after its original node is shut down in AKS.
Pod eviction time can be reduced from five minutes to seconds by setting tolerations for not-ready and unreachable nodes in the deployment YAML.
By adding tolerations to the nginx deployment, a new pod is spun up on a healthy node just ten seconds after the original node fails.
A demo with SQL Server shows that even with tolerations, the new pod gets stuck in a "ContainerCreating" state due to a multi-attach error on the persistent volume.
A third-party tool called Portworx provides a storage class that correctly detaches and reattaches storage, enabling a SQL Server pod to fail over successfully in seconds.
Achieving high availability for stateful apps in Kubernetes requires adjusting pod tolerations and using a storage solution that can handle volume reattachment across nodes.
48:45Denis Souza Rosa
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21:43Mario Valderrama
42:45Marc Nimmerrichter
57:09Stijn Polfliet
29:30Wei Hu
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