I'm currently doing some work on monitoring SQL Server performance. I've found the following script which calculates 'Page Lookups Percentage' - the suggestion being that a "good" value is something less than 100.
SELECT 1.0*cntr_value / (SELECT 1.0*cntr_value FROM sys.dm_os_performance_counters WHERE counter_name = 'Batch Requests/sec') AS [PageLookupPct] FROM sys.dm_os_performance_counters WHERE counter_name = 'Page lookups/sec'
Now I've run this script on about a dozen different servers - mostly virtual but a couple physical, mostly 2008R2 Enterprise but a couple of 2005, some live and some development, and even a physical 2008R2 Express edition that has only ever been a witness server and is currently dormant (no mirrors set up with active failover). On only one of these servers has the value been below 100. In most cases it has been in the 1000's or at least in the mid 100's. On the dormant witness server the value was a ridiculous 20,000 !
Does this indicate that we have widespread problems in this area, or is there some innocent explanation for why this figure should be so high on so many different servers? We are experiencing slow performance on some of these servers, so it would be useful for me to get a better understanding of what this figure is telling me.