Reports in SSMS are very helpful when monitoring SQL Server. But today I encounter an issue with one of the reports, which is Disk Usage Report.
Above is the Transaction Log space usage report taken for same database but for different times. Actually, second one was after taking a log backup. After seeing this report my immediate reaction was log backup has not cleared the log. So I ran another log backup and results are similar. But when you analyze these graphs carefully you would see that in the first graph, Green is Used and in the second Green is Unused and Blue is vice-versa. (Oops).
I did few more research into this to find out the tipping point and this is happening after 50% percent. See the image below.
Now it is 50-50 and next one is,
You can clearly see the change. I verified this is the same behavior in SQL Server 2008 R2 as well.