I m curently upgrading our elasticsearch single node from 1.4.2 to 6.1. The new version is installed on a new server but the new logstash receive the same data (mainly logs). I have a really strange behavior, The new server write continuously 100-150 M/s (info from iotop) and the old one only a few M/s. I have the same behavior when I do a request, the new server read about 100-150 M/s and the old one only a few M/s.
I have no idea how to analyze this. Any help welcome.