What is the McShield service? A quick Bing search revealed that it’s one of the services for McAfee VirusScan Enterprise. Could this be the cause? To get a quick look at all the history, I filtered the application log for event IDs: 17890 and 5000. Each time McAfee got an updated virus DAT file, SQL Server soon followed that by paging out the entire buffer pool. I checked the application log on several other SQL Servers for the same event IDs, and sure enough the same events occurred in tandem each morning. I also got confirmation from the security administration team that McAfee is scheduled to check for new DAT files each morning around 8AM. Eureka!
This seems like it could be the cause of our paging, but a little more research is needed. Searching the McAfee knowledge base, lead me to this article about the “Processes on enable” option.
Enabling this option causes memory pages of running processes to get paged to disk. And the example given is “Oracle, SQL, or other critical applications that need to be memory-resident continually, will have their process address space paged to disk when scan Processes On Enable kicks in”. OUCH! So when the McAfee service starts up or it gets a new DAT file, it will page out all processes.
Fortunately, this is a setting you can turn off, and Patrick shows how.