• Are you having a downtime on your SQL Server?

• Do you have slow running queries?

• Are there any blocking or deadlocks?

• Is there any running maintenance (backups, index fragmentation, dbcc etc.)?

• Did you initiate any version upgrade of SQL Server (2008, 2012,2014, 2016, 2017 etc.)?

• Any partitioning implementation?

• Is the server a shared SQL Server instance?

• Do you have OLTP and reporting service on the same server?

What is the previous "Baseline" state of the system? 

• What is the used and available memory?

• Do you encounter CPU bottlenecks?

• What is the status of HA/DR synchronization and components?

• Do we have disk latency?

• Are you having high waits?

• Any automatic scheduled jobs implemented or change?

• Do you have baseline for the top executing queries?

• Any system change/deployment done?

Any idea about System Configuration and it's impact?

• Any changes on Server, Instance and Database settings?

• Is the server Physical or Virtual Machine (VM)?

• Have you correctly allocated the number of sockets and logical processor in the server?

• Did you correctly configure the memory?

• Any volume partition alignment?

• Did you consider Lock Pages in Memory and Instant File Initialization?

• Have you check the Power Management?

• Have you checked the BIOS settings?

• Have you checked the Database settings?

How to begin with your System Health Checks?