We have an Hadoop cluster of CentOS 6 (kernel version 2.6.32-504.el6.x86_64) and CentOS 7 (kernel 3.10.0-327.el7.x86_64) servers .
All the nodes are configured with a swapinness of 1. All nodes have plenty of RAM availables.
The CentOS 6 nodes never swap any processes but the CentOS 7 nodes swap processes even if there is available memory. This triggers warning in our monitorig tools.
Can someone explain me why my CentOS 7 nodes behave differently than the CentOS 6 nodes and what I can do to prevent swapinness? Apparently, configuring swapinness to 0 can lead to issues so I'm not confident to do it.
Thanks in advances, Loïc