Marios,

I just ran across your post. I know you've had some SQL Sentry training recently so hopefully these and any other questions have already been answered, but I wanted to go ahead and respond just in case.

You are correct, the SQL Server Memory Page Reads/Writes chart shows any time SQL Server reads or writes buffer data to/from disk. On the left you'll note the Windows Read/Write Faults chart with similar palette shows pretty much the same thing, but for Windows. You generally want both of these charts to be as close to zero as possible since it means data is staying in cache and not being continously paged to/from disk because of insufficient memory.

There are some times SQL Server paging will be above zero and it's ok, including:

- checkpoints

- tempdb activity (depends on type and level of activity)

- index rebuilds/defrags

- backups

However, if you see continuously high SQL Server paging when these activities are NOT happening, and it correlates with low page life expectancy (<300 seconds), lazy writes, and/or high disk latency (all of which are also shown in this area on the dashboard), then yes, more than likely you have some memory pressure. To determine which queries may be causing churn, simply highlight any range where you see high paging, then select Jump To->Top SQL, then sort the grid descending by reads or writes. In "Show Totals" mode it will strip any parameters and provide aggregates over the range. Focus on the queries with the highest IOs first -- take a look at the plans, and look for scans, sorts, or other potentially IO-heavy operations. (In our next release, 5.6, you'll be able to do this directly from the Top SQL tab!)

We will be publishing more about how to interpret the metrics we show in the very near future... keep any eye on the SQL Sentry documentation, as well as my blog, http://greg.blogs.sqlsentry.net . In the meantime, I highly recommend checking out the SQL Server Waits & Queues whitepaper as it covers many of them:

http://msdn.microsoft.com/en-us/library/cc966413.aspx?ppud=4

Greg Gonzalez

President, SQL Sentry