The Average Physical I/O Times graph plots the average amount of time spent performing physical reads and writes for a buffer pool. The graph contains separate series for reads and writes:
Reads —Shown in light blue, this series plots the average amount of time spent physically reading data or index pages into a buffer pool from tablespace containers.
Writes—Shown in orange, this series plots the average amount of time spent physically writing data or index pages from a buffer pool to disk
The times spent on physical reads and writes are averaged from statistics accumulated since a database was started or statistics were reset. They are shown in milliseconds on the vertical axis. Check these values along the horizontal axis to see how average times are changing over consecutive monitoring intervals of ten minutes.
Note: Check the Statistics tab to see counts for physical reads.