Significantly higher Read IO usage after upgrade from 10.7 to 10.11

[S Bob <sbob@xxxxxxxxxxxxxxxxxxxxx>]

All;


After a minor version upgrade from 10.7 to 10.11 we are now seeing 
almost double the IO usage for reads, our traffic has increased slightly 
but not nearly enough to justify double the read IO usage.

Any known issues that could explain this?


Thanks in advance