I think high memory usage on the OS is inherent to the memory intensive requirement of SOLR. I've observed SOLR wanting to swap on the OS when performing queries.
Is it recommended to try to prevent the system swapping by reducing the value swappiness in RedHat?
For example, at the moment our SOLR instances are swapping and swappiness it set to 30, which basically means that when less than 30% memory is available the OS is inclined to swap. I don't think it's advisable to set it to 0, but my understanding is that setting it to 5 would make the OS less likely to swap.
Any thought/experience with this?