The Data Read Rate graph depicts rates for retrieving data pages from the buffer pools for the application 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 data page read requests directed at the buffer pool.
Physical —Plots the rate at which logical read requests required actual database I/O to get the data pages into the buffer pool first. When the physical read rate is persistently higher than the logical read rate, the buffer pool is not being used effectively.
The Statistics tab shows the buffer pool read counts used to generate this graph. The names for these statistics begin with Buffer Pool.