We are experiencing high disk I/O latency in a specific timeframe in SQL Server. Every day at exactly 4:30 AM we see a significant difference in disk I/O and it lasts up to 6:30 or 9:30 AM. I already checked with the development and storage teams. They confirmed that everything is running normally. Storage team declared that there is no issue in LUN and they are blaming SQL Server.
One thing is sure--some job is triggering exactly at 4:30 AM every day, which causes the high disk I/O. But I am not sure how to find that out. I attached the screen shot of the SQL error log at 4:30 AM. All the monitoring tools and the logs are stating that the transactions are taking longer that usual due to high disk I/O. But nowhere is it mentioned what is causing it.
Ours is 3 node Always On environment. P1 - primary, P2 - Stand only, P3 - Read only.
The issue we are facing now is from P3 (Read only node).