On 20/11 starting from 8:00 A.M the application got "Timeout expired" error messages.
We noticed database performance degradation.
The DB was up, accepting connections but most of the queries (on different tables) were running very slow. (e.g: 3 minutes instead of several seconds)
During this time, the CPU was less than 40%, memory was stable ~ 85%.
There were no locks, nor load on the database.
The problem was solved after restarting the SQL Service.
No error messages detected in the Cluster, the virtual host, SQL logs and in the server event viewer.
Please guide us how can we find the root cause of the problem,
how to avoid it, and what else can we check if we hit the same problem again.
Configuration
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WIndows cluster on hyper-V
OS Name: Microsoft Windows Server 2016 Standard
OS Version: 10.0.14393 N/A Build 14393
Each cluster server has 16 CPU, 64G Ram
SQL Server version: Microsoft SQL Server 2017 (RTM-CU11) – 14.0.3038.14
Kiran