Day 5 – Blocking by Hour of Day

The Blocking by Hour of the Day report is one of the instance level reports available in Database Health Monitor.

Important Note: The blocking percentages are relative for the date range shown. We find the hour that has the most blocking and use that as the maximum. All the percentages are calculated based on the percentage of the maximum blocking amount.

100% is shown for the hour that has the most blocking, not indicating that we are 100% blocked.
50% shows that that hour had half the blocking that the biggest blocking hour had.
0% does not mean that there was no blocking at all. It indicates that if there is blocking that it is less that half of 1% of the maximum blocking amount.

This chart is used to find the hours of the day that blocking occurs the most. If you are seeing trends here on a day to day basis you may want to do additional tracking during those busy hours.

This is one of my favorite reports to find trends that are perhaps related to maintenance jobs or other scheduled items. It will also help find if blocking is occurring during the busiest times of the data that the system is being used.

By default the report shows you the last 7 days as columns and each hour of the day as a row with the amount of blocking for that hour shown in the block. The buttons “show more” or “show less” at the top will allow you to look at 2, 3 or even 4 weeks of blocking history.

To use the Blocking by Hour of Day report, you need Historic Monitoring enabled for your SQL Server instance. You can get to this report by going to the Server Overview page and clicking the gray button in the instance report section for “Blocking By Hour”.

Day 5 – Blocking by Hour of Day

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