At runtime we issued a query cache size change. We reduced it significantly.
This process run for about 4 minutes.
On the graphs we seen during this period increased disk reads, approximately 18MB/s.
We can't explain why this change needed disk reads, and why so much? As what we expected is that it will prune the cache from the RAM, and nothing else. Anyway we did not expected disk reads at this size.
How do you explain?