Connections

This resource shows the status of your current database connections. The icons of the listed performance counters in the Statistic Name column change colors to reflect the listed counter's current state. Clicking any performance counter in the Statistic Name column takes you to the Performance Counter Details page for that performance counter.

If the value of a listed performance counter crosses the Warning threshold, the chart for the listed counter displays a yellow background. If the value of a listed monitor crosses the Critical threshold, the chart for the listed counter displays a red background. Hovering over any time period within the chart displays detailed information about that time period in the tooltip. Hovering over a counter gives you detailed information about that performance counter.

Counter Expert Knowledge
User Connections

The User Connections performance counter identifies the number of different users that are connected to your SQL Server at the time the sample was taken.

You need to watch this performance counter over time to understand your baseline user connection numbers. Since each user connection consumes some memory space, a high number of user connections can impact throughput and cause a performance slow-down. Once you have an idea of your high and low thresholds during normal usage of your system, you can then look for times when this counter exceeds these high and low marks.

Potential Issue: If the returned value of this performance counter goes down and the load on the system remains stable, you might have a bottleneck that is not allowing your server to handle the normal load. Keep in mind that this counter value might go down just because less people are using your SQL Server instance. If you see this number jump by 500% from your baseline, you may be seeing a slowdown of your server activity.

Resolution: You may want to boost the SQL Server configuration setting, Maximum Worker Threads to a figure higher than the default setting of 255. The setting for Maximum Worker Threads should be higher than the maximum number of user connections your server ever reaches.

Logins/sec

This performance counter returns the total number of logins started, per second, and does not include pooled connections.

Opening and closing connections is an expensive process. A pooled connection is one which is kept open by an application for other requests to re-use.

Potential Issue: If the returned value is high, this can indicate that the application is not correctly using connection pooling.

Resolution: Review the Connection Polling configuration.

Logout/sec

This performance counter returns the total number of logout operations started, per second.

Opening and closing connections is an expensive process. When applications do not use a connection pool, each request needs to establish its own connection before the query can be executed. It then has to close it. A pooled connection is one which is kept open by an application for other requests to re-use.

Potential Issue: If the returned value is high, this can indicate that the application is not correctly using connection pooling.

Resolution: Review the Connection Polling configuration.

Zooming

You can have the chart show a predetermined time period of data by clicking on any one of the three Zoom buttons in the head of the Zoom column. Alternatively, you can have the chart show a specific date range by dragging the mouse over an area of the chart. The time and date displayed at the top of the resource shows the amount of data currently loaded into the chart. This can be changed by clicking Edit from within the resource.

The Value from Last Poll column shows the most recent data available for the listed statistic.