Monitoring Paging Activity
Which performance counter to use to monitor hard page faults.
Performance Monitor can be used to monitor all kinds of activities on Windows systems, but it can be tricky to figure out which counter you need to watch in order to look for a specific type of activity. For example, an administrator asked me why his server was averaging 50,000 page faults per second. I said, Wow! Then I asked him which counter he was monitoring and he said Page Faults/sec. So I pointed out to him that page faults don’t necessarily indicate disk activity i.e. hard disk reads, and that he should look at Pages/sec instead if wanted an indicator of the number of hard faults per second, which of course turned out to be a lot lower.
Moral of the story? Page Faults/sec includes both hard faults (involve disk access) and soft faults (where the faulted page is retrieved from RAM) so it’s Page/sec that you want to look at if want to measure disk activity related to paging.
Mitch Tulloch was lead author for the Windows Vista Resource Kit from Microsoft Press, which is THE book for IT pros who want to deploy, maintain and support Windows Vista in mid- and large-sized network environments. For more information see www.mtit.com.