Strange results in io_usage table
I have been looking at the various informational tables to see if I can identify some performance problems and I was looking at the io_usage table and I am seeing very strange results. The written_kbytes_per_sec always far outweighs the read_kbytes_per_sec. While this might make sense during some small part of the day when I am doing a lot of data loading, further investigation shows that it is always that way throughout all the time that the database is being used (primarily just for select queries): hour total_read total_written 7 0.13 662.39 8 125.73 70,081.81 9 150.37 80,543.02 10 69.04 80,512.73 11 71.29 80,758.04 12 93.7 80,891.69 13 247.98 80,669.46 14 4,551.3 81,476.16 15 216.37 9,596 That doesn't make sense to me, it seems like there would be a whole lot more reading going on than writing. Am I interpreting this data wrong? Why would this be?