AAG on Linux : Pacemaker and corosync

Question

https://learn.microsoft.com/en-us/sql/linux/sql-server-linux-availability-group-ha?view=sql-server-ver15

Not quite under stand why in the following situation (Primary failed), it still can do auto failover

And what;s the difference between pacemaker and corosync? what are there responsibility ?

how pacemaker detect the sql server is healthy or not ?

Answer 1

Hi @sakuraime ,

> what;s the difference between pacemaker and corosync? what are there responsibility ?

Pacemaker - The core clustering component, that does things like coordinate across the clustered machines.
Corosync - A framework and set of APIs that provides things like quorum, the ability to restart failed processes, and so on.

Please refer to Pacemaker for Always On Availability Groups and failover cluster instances on Linux.

> how pacemaker detect the sql server is healthy or not ?

When AGs or FCIs are configured on a Windows-based configuration, they are cluster-aware. Cluster awareness means that SQL Server has specific resource DLLs that a WSFC knows about (sqagtres.dll and sqsrvres.dll for FCIs, hadrres.dll for AGs) and are used by the WSFC to ensure that the SQL Server clustered functionality is up, running, and functioning properly. Because clustering is external not only to SQL Server but Linux itself, Microsoft had to code the equivalent of a resource DLL for Linux-based AG and FCI deployments. This is the mssql-server-ha package, also known as the SQL Server resource agent for Pacemaker.

Please refer to Install SQL Server packages for availability.

Please refer to
Best regards,
Cathy

---

If the response is helpful, please click "Accept Answer" and upvote it.
Hot issues October--Users always get connection timeout problem when using multi subnet AG via listener. Especially after failover to another subnet