The Index Read Rate graph depicts rates for retrieving buffered index pages belonging to the selected tablespace over consecutive monitoring intervals. These rates are based on the number of pages read per second. The graph contains the following series:
Logical —Plots the rate of read requests for index pages (belonging to the tablespace) that are already in the buffer pool.
Physical —Plots the rate at which logical index page requests required actual I/O on the tablespace to get the index pages into the buffer pool first. When the physical read rate is consistently higher than the logical read rate, the buffer pool is not being used effectively.
The Statistics tab shows the buffer pool write counts used to generate this graph.