I recently have upgraded my ES from 1.5.2 to 2.2.0 version. When I`m inserting data to the 2.2.0 cluster I can see that the i/o is incredibly higher then before:
1.5.2: ~30 average, 300 peak
2.2.0: ~900 average, 1122 peak
Is this a normal behavior, or is it too high and need to be fixed?